Nile, modern hydrology
Statistics on Nile discharge at Aswan begin in 1871, and by 1912 for the major tributaries in Sudan. Despite a trajectory across nine modern countries, 83 percent of the waters reaching Egypt come from Ethiopia: 55.8 percent from the Blue Nile, 13.8 percent from the Atbara, and 13.3 percent from the Sobat rivers, which respectively drain the center, north and west of that mountainous nation. Only 16.5 percent of the Nile waters entering Egypt come from the equatorial lakes, and about 50 percent of that discharge is evaporated in the Sudd swamps of southern Sudan that filter out half of the year-to-year variability, delay the seasonal maximum by two months, and trap most of the sediment coming from Uganda, Zaire, Tanzania and Kenya. The Bahr el-Ghazal of southwestern Sudan contributes only 0.6 percent of the discharge reaching Egypt. Apart from modern water use for irrigation, there are substantial losses due to evaporation and net percolation to subsurface aquifers as the Nile flows across the Sahara, including 4.5 percent between the Atbara confluence and Aswan.
Despite the valid reputation of the Nile as a dependable water source, reflecting runoff derived from different climatic regions, variability is significant. Mean discharge at Aswan was 15 percent higher for the years 1871-1905 than for 1905-65, and that for 1840-1900 (using less reliable earlier measures) probably was 30 percent greater than during the twentieth century. The lowest annual volume (in 1913) was 45.5, the highest (in 1978), 150, compared with a mean of 84 milliard m3; or a range from -46 percent to +79 percent. These deviations tell only part of the story: the coefficient of variation of the annual Nile volume at Aswan 1912-73 was low at 18.5 percent, but that for Nile flow during the peak month of September was 32.8 percent, reflecting (a) the less predictable date of the flood crest, between 20 August and 19 October, (b) the concentration of discharge in a single, short but high peak, of as little as twelve days, or a series of longer but lower crests (spanning up to fifty days), and (c) the maximum flood elevation attained (within a range of 2.75m).
There are other important complications. For the period 1902-63 (prior to the impact of the High Dam), the Blue Nile provided 68 percent of the flood discharge and 72 percent of the critical increment of sediment for Egypt. However, these proportions vary with climatic trends. Southwestern Ethiopia was unusually wet in 1962-81, as was the basin of the Victoria Nile, while central Ethiopia experienced an attenuated drought in 1965-86. Consequently, the annual contribution of the Blue Nile declined by 15.4 percent for 1962-86, while that of the White Nile increased by 19.8 percent (with respect to the mean for 1912-86). The proportion of White Nile waters thereby increased from 30.4 percent to 36.4 percent. But in Egypt, White Nile discharge dominates during the low-water stage, from December to June, and adds no fertile sediment to the fields. The Atbara, representing trends in northern Ethiopia, was in phase with the Blue Nile during the first half of the drought years, 1963-74, but during 1975-83 its discharge was well above average.
An excessively dry or wet year is far more likely to be felt throughout Ethiopia than is a trend that lasts a decade or more. Nonetheless, the last decades of the nineteenth century were evidently wet in both central and southwestern Ethiopia. In general, the several contributions of the main affluents of the Nile do not covary, and their relative influx during historical and prehistoric times will have fluctuated considerably.
Nile Valley, geological evolution
One of the world’s longest rivers (6670km), the Nile spans some 34 degrees of latitude, from 2° south of the equator to 32° north, at the tip of its delta. It draws its waters from the Ethiopian Plateau (Lake Tana at 1830m elevation) and the lake district of equatorial East Africa (Lake Victoria, 1134m). Yet its drainage basin is only of moderate size (2.87 million km2), about half of which contributes next to no runoff, and its volume is less than half that of the Danube.
The irregular watershed of the Nile cuts across several tectonic provinces, with a complex geological history that remains imperfectly understood. A river did run northwards, near the course of the western Egyptian Nile, since at least Oligocene times (some 40 million years ago), but it did not yet tap into the sub-Saharan basins of the Blue and White Nile. The updoming of Ethiopia began 30 million years ago, with the capping basalt flows in place 24 million years ago. That would have directed much of the Ethiopian drainage toward the older sedimentary basin in southern Sudan. Uplift and initial erosion of the Red Sea Hills 20 to 17 million years ago began to define the axis of the Saharan Nile, connecting the Blue Nile drainage by 5 million years ago.
The landscape of Egypt consists of three main components: (1) the Eastern Desert, (2) the Western Desert and (3) the Nile Valley.
(1) The eastern perimeter is formed by a spine of ancient igneous and metamorphic rocks, upfaulted from the African Shield to form the Red Sea Hills of the Eastern Desert. Rough and jagged in profile, these low ranges are interrupted by small basins and cut by west-east drainage lines that facilitate travel from the Nile Valley to the Red Sea.
(2) The bleak plains and plateaus of the Western Desert stretch westward from the valley, and are level and tabular. They are formed by multiple horizons of sedimentary rocks, exposed to erosion for more than 100 million years in the south (Cretaceous: Nubia Sandstone) and 20 million years in the north (Miocene limestones). At great intervals there are steep escarpments or shallow depressions, partly excavated by wind action, that intersect aquifers to provide springs that sustain oases such as Dakhla and Kharga.
(3) The Nile Valley is incised into the erosional surface of the eastern Sahara, running roughly parallel to the axis of the Red Sea Hills on its northward course to the Mediterranean Sea. Through Nubia, the valley is shallow and cut into Nubia Sandstone, with local thresholds of hard, igneous rocks that form six cataracts between Khartoum and Aswan. A tectonic basin intersects the valley at Kom Ombo. Near Esna, high cliffs (200-500m) of Eocene limestone (some 50 million years old) close in on the valley, remaining prominent downstream to Minya. From there the margins of the valley open up, with sand-swept plains to the west, and open hill country to the east. The Fayum Depression, its bedrock floor 50m below sea level, has overland and subsurface links to the Nile, with a more shallow counterpart in the Wadi Natrun.
Deep entrenchment of the Nile Valley and its delta is dated to the Messenian (6 to 4 million years ago), when the Mediterranean Sea dried up and a remarkable canyon was cut by river action, facilitated by crustal movements, to 2000m below modern sea level near Cairo, and 175m below sea level even as far upstream as Aswan. During the subsequent 2 or 3 million years, this over-deepened canyon was filled with marine, estuarine and fluvial beds, remnants of which remain visible along the valley margins. But the weight of accumulating sediment in the Delta continued to depress the underlying crust, now as much as 4km below the surface.
During the last 1-2 million years, sweeps of river gravel were washed together as river terraces, at progressively lower levels below the desert cliffs, fragmentarily preserved at elevations of 60 to 15m above the modern floodplain of the Nile. These gravel "terraces" contain a small fraction of sands derived from the Upper Nile Basin, and at least the younger units show evidence of early Paleolithic occupation, such as Acheulian handaxes. Distinctive Ethiopian flood silts first appear as interbeds within Acheulian terrace gravels, and after about 75,000 years ago the Nile ceased to accumulate gravels and switched to its modern regime of summer, flood silts. This change was not the result of a shift in behavior of the Upper Nile, but of the tributary wadis in the Egyptian deserts; their channels became almost defunct, with only sporadic activity since that time.
An archaeological record for continuous human settlement in the Egyptian Nile Valley only begins roughly 20,000 years ago, represented by Late Paleolithic industries, some of which evolved into the Epi-paleolithic hunting-fishing-gathering economies of the early Holocene.
Egypt was divided into a series of districts or provinces, called nomes, from an early point in its history. The problem of when and how the nomes were created in Egypt for administrative purposes has not yet been definitely resolved. Certainly they existed at the beginning of the Old Kingdom; inscriptions giving names and titles of nome administrators (nomarchs) were discovered inside the Step Pyramid of King Zoser at Saqqara.
The nomes were characterized either by an emblematic sign mounted on a standard designating a particular district, by the hieroglyphic sign for nome as a general term for a district, or by a combination of the two. The expression "nome" derives from the Greek word nomos, denoting a local or more accurately a regional administrative unit of the country during the Graeco-Roman period. Therefore, the term "nome" may be applied to any administrative subdivision at the regional level; it is not important whether or not the name of the nome is written with the canonical nome sign and whether or not its area coincides with that of the traditional nomes symbolized by a nome emblem.
The traditional nomes written with nome emblem or canonical nome sign were administrative entities only during the Old Kingdom. These original nomes lost their importance as administrative subdivisions during the First Intermediate Period, at least in the southern part of the country. In the Middle Kingdom they were replaced by other administrative units, the town districts consisting of towns and their surrounding area.
The name of the town was used to designate both the town and its district, the new "nome."
In spite of having lost their functional importance, the original nome symbols were still used in later times in geographical and especially in religious contexts. Thus, the most complete lists of the traditional nomes are preserved in temples of the Graeco-Roman period, where processions of nome personifications are depicted bringing offerings. Only in this context are the traditional forty-two nomes of Egypt mentioned: twenty-two in Upper Egypt and twenty in Lower Egypt. These geographical lists use traditional forms and names common in the remote past—a phenomenon not uncommon in the religious sphere—but they do not represent the contemporary administrative division of the country. Administrative documents of the same time did not use these designations, even if they were written down on the walls of Egyptian temples like the donation text of Edfu. The twenty-two Upper Egyptian nomes mentioned in these lists coincide with those known from the Old Kingdom. Some of the twenty Lower Egyptian nomes seem to have been artificially created during the Late period for religious reasons, and reflect in their own way the changes within the nome structure in the Delta.
The nomarchs, or nome administrators, were responsible for civil administration in their nomes. The hieroglyphic sign for "nome" (sp3t), used to designate the administrative unit during the Old Kingdom, shows a grid of lines at right angles. According to Egyptological tradition, this indicates a plot of land furrowed with irrigation channels. The importance of irrigation during the Old Kingdom is seriously debated today, and this explanation can no longer be accepted. The sign represents land with clearly defined subdivisions or fields, divided and registered for cadastral purposes. The registration of the land was the basis of all administrative activities in the country. The most important duty of the nome administrators was to levy and collect taxes, mainly agricultural products but also the corvee of people attached to the land for temporary work for the state. Officials of the nome administration are explicitly mentioned as being responsible for this work in royal decrees from the Old Kingdom exempting temples from various kinds of service and taxes. In their tombs in Beni Hasan and Elkab, nomarchs of the Middle Kingdom and of the New Kingdom, respectively, are depicted collecting taxes in their districts.
In the late Old Kingdom nomarchs were called "great overlord of a nome." Later this became an honorific title; from the Middle Kingdom onward a new title was introduced to designate the chief administrator of a nome. This title is normally translated as "mayor." This translation can give the false impression that this official held responsibility only over the nome capital, which is incorrect. The whole district in its entirety was under this official’s jurisdiction. This title was also used to designate district administrators in Nubia particularly during the New Kingdom, when Nubia was part of the Egyptian empire.
The art of fortification reached its highest point before the Romans in the strongholds built in Nubia by kings of the Egyptian 12th Dynasty, in a chain that extended from Aswan (Elephantine) to the southern end of the Second Cataract at Semna (21°30′ N, 30°57′ E).
From very early times, the Egyptian government was concerned with frontier security, especially in Nubia, and the first actual fortification discovered there was on the island of Elephantine, dating at least as early as the 1st Dynasty, circa 3,000 BC. Its location on the newly established southern frontier of Egypt is significant, for Egyptian power had demolished concentrated occupation (of the local A-Group peoples) in the Nile Valley south of the First Cataract.
The centralized Egyptian monarchy viewed fortifications as belonging either to the state or to rebels, and the storming and destruction of forts was a standard theme of official art. The construction of strong points was also commemorated, in inscriptions and in the aggressive names sometimes given to fortresses on the frontier. The true fortresses erected at the frontiers, especially in the Middle Kingdom, controlled access to Egypt, secured bases for mining and quarrying expeditions, and provided forward positions for military campaigns.
Although usually attributed to economic motives, the 12th Dynasty military occupation of Nubia had its background in the extended wars, disturbances and instability of the preceding period. The Nubian Nile Valley had been intensively resettled before the end of the Old Kingdom, circa 2,400 BC, and during the First Intermediate Period Nubians entered Egypt in sufficient numbers to play an important role in the military establishments of local and regional rulers as far north as Asyut. They established their own settlement north of Aswan and even acquired important positions in the 11th Dynasty court at Thebes. For a brief time, there was even an independent dynasty in Nubia that included one ruler with a Nubian name who fought against forces from the north. It was probably this dynasty that erected an administrative and possibly fortified complex near Amada. The Amada "fort" consisted of two rectangular mudbrick structures with irregular additions of enclosures and pens, all linked into a single walled complex. Although the 11th Dynasty campaigned in Nubia, it was not until the 12th Dynasty, during the reign of Senusret I, that the first real conquest of Lower Nubia was accomplished. While economic interests may have played a role in Senusret’s conquest,he probably undertook this conquest, along with the establishment of fortresses and the stabilization of the frontiers, to increase the security of the borders and to reduce or eliminate the numbers of foreign soldiers in the private armies of his governors (nomarchs).
The 12th Dynasty rulers reversed the anti-settlement policy of the Early Dynastic period and Old Kingdom, when only a fortified industrial site near Buhen (21°55′ N, 31°17′ E) is known. Instead, the 12th Dynasty government maintained a chain of mudbrick fortresses to protect its interests among a population that retained its own culture, and became, if anything, more prosperous and numerous under Egyptian rule.
The exact date when each of the seventeen fortresses of the Nubian complex was founded is not always clear, but the first part of a system was almost certainly put in place by Senusret I. Forts at the Egyptian frontier probably already existed, at Elephantine and Biga (in Egyptian, "Senmet") islands, and possibly as far north as Gebel Silsila. New were the round-bastioned structures at Ikkur and Kuban ("Baki," 23°10′ N, 32°46′ E) on the west and east banks of the Nile at the entrance to the Wadi Alaqi, Aniba ("Miam," 22°40′ N, 32°01′ E), at the largest center of the local C-Group culture, and Buhen, at the southern end of C-Group settlement in Lower Nubia. A fortified industrial site was established at Kor (21°52′ N, 31°14′ E) near Buhen, which grew into a large administrative and trading (?) center.
Although these fortresses provided security and possibly some logistical support for wide-ranging renewal and expansion of mining and quarrying activities as well as trade, they were not nuclei for Egyptian settlers. The necessary evidence of permanent settlement, Egyptian townsites and burials, rarely occur in Nubia during the 12th Dynasty. Egyptians in Nubia at this time were transitory garrison soldiers, workmen and administrators. Evidence of the fortresses’ function is preserved only from the New Kingdom, but the archaeological evidence of the C-Group in Lower Nubia suggests that this occupation was stabilized, with little of the cultural change or diversity that marks their remains south of Egyptian control. It is noteworthy that the forts of Ikkur and Kuban are located where the Wadi Allaqi enters the Nile Valley. This wadi was the main route to the Nubian gold mines and the most important route for infiltration from the Nubian Desert. For a century or so, the peoples of Lower Nubia were controlled by the Egyptians.
The threatening rise of the Nubian kingdom of Kush, centered at Kerma, and allied powers in the south, and possibly worsening conditions in the Eastern Desert, made this policy obsolete by the time of Senusret III. He repeatedly campaigned against Kush, which was part of a greater political agenda also evident in his campaign in Palestine, his suppression of the powerful nomarchs in Middle Egypt, and a new bureaucratic state apparatus. This new policy was strongly evident in the military administration of Nubia.
For all Senusret III’s boasting in his texts carved on the Semna Stelae, the campaigns must have been hard fought and may have been inconclusive. The older fortresses were rebuilt and a new frontier was established at Semna, the narrowest point on the northern Nile, where the largest and most complex system of fortifications known to precede the Roman military frontier (limes) are found. The complex of fortifications he completed in Nubia was the greatest secular construction to survive from ancient Egypt. It is one of the ancient world’s most impressive feats of military planning, architecture and engineering. In terms of organized state projects, it represents the effort that might have been required to build several Middle Kingdom pyramids. The fortresses and the boundary they protected were administered with a rigorous detail hardly seen before the rise of modern police states.
The old forts in Lower Nubia proper, Ikkur, Kuban and Aniba, and presumably also Elephantine and Biga, were expanded and enhanced. The other older fortresses near the frontier, Buhen and the fortified center at Kor, were greatly expanded, but otherwise the forts were new.
The Nubian frontier was concentrated in the region of Heh (21°30′ N, 31° E), comprising the forts of Kumma ("Itnuw-Pdjut," 21°30′ N, 30°57′ E) on the east bank, and Semna ("Sekhem-Khakaura’ Ma’-kheru") and Semna South ("Dair-Seti," 21°29′ N, 30°57′ E) on the west bank, and the island fortress of Uronarti ("Khesef-Iunuw," 21°32′ N, 30°57′ E). The two west bank fortresses were linked together by a low wall that isolated an area where vessels could be beached. Here at the large granite outcrop of the Semna Cataract, the main channel of the Nile was less than 50m wide at low water. At the northern end, this complex of forts was anchored by the fortress of Uronarti, which was located on a large island with a palatial administrative complex.
The distance between the Semna complex and the Second Cataract proper (circa 40km to the north) was secured by two fortresses, Shalfak ("Wa’f-Khasut," 21°33′ N, 31°02′ E) on the west bank, and Askut ("Djer-Setiu," 21°38′ N, 31°06′ E), on an island farther north. Beyond Askut, the Nile is broken entirely into a cataract of braided channels and is impassable to shipping, particularly at low water. The large fortress of Mirgissa (21°49′ N, 31°10′ E) was located at its upstream end. The cataract was bypassed below Mirgissa by a mud-paved slipway along which boats were dragged, apparently on low runners. This slipway extended in a straight line some 8km to a point above the rock of Abusir, almost to the great fortified center of Kor (ancient name unknown), now greatly expanded and given elaborate fortifications to accommodate large official complexes. Just to the north was Buhen, also greatly expanded and with fortifications of considerable sophistication. The cataract region complex was completed by the establishment of two smaller fortresses, at Faras West ("Ink-tawy," 22° 13′ N, 31°29′ E) and Serra East ("Khesef-Medjay," 22°07′ N, 31°24′ E), not far to the north.
The fortresses dating to the reign of Senusret III have various plans, adapted to controlling their situation and keeping ready access to the river. Most were rectangular, with one wall fronting the Nile, but others had shapes adapted to the available high ground: Semna was L-shaped, while Uronarti and Askut were roughly triangular. The smallest (Kumma, Semna South) were about 50m sq., while the larger ones (Buhen) were about 200m sq. The great outer wall at Buhen extended some 700×250-300m.
The details of construction varied somewhat, but can be summarized as follows. First, the ground was cleared and leveled to bedrock as far as was practicable. The outer perimeter of the fortress was surrounded by a ditch with sloping sides and a flat bottom. Where bedrock and space allowed, the ditch was cut from stone, but otherwise lined with stone masonry or even mudbrick. The surface inside the ditch was paved, either with stone or mudbrick, up to the platform of the inner curtain. At most of the forts on the river banks, the parapet of the ditch was crowned with a low mudbrick wall of variable elaboration. For example, at Serra East this was a simple straight wall, while that of the inner citadel of Buhen had convex bastions, shield-shaped crenellations, and complex groups of loopholes that would allow an archer to shoot arrows in several directions with a minimum of exposure. At Buhen the outer parapet of the ditch was also walled, but it is difficult to understand the purpose of such a construction except as a low barrier to keep animals from sliding into the ditch. The curtain was located about 2m (sometimes more) behind the edge of the ditch. At Serra East, this was built on a shallow layer of sand laid on the subsurface. The core of the curtain was a wall of mudbrick courses, of alternating headers and stretchers about 5m (or more) thick. Thick mats of local halfa grass were laid at intervals, especially in the lower courses where the wall was thickest.
In some forts, notably those built on rocky hills or bluffs (Askut, Shalfak, Semna, Kumma, Uronarti, Serra East), the mudbrick was reinforced, sometimes heavily, with timber, including both longitudinal and transverse beams, while Mirgissa had only transverse logs. Rectangular piers (some 2m deep by 3m wide) were built against the outer face, generally with mud plaster making sloping lower faces, but were much wider at the corners. In some cases, such as Mirgissa, the walls had flat pier-like bastions, but most of the forts were also equipped with spur-walls or towers which were connected to the main wall only by a passage on the wall parapet, and barbicans, pairs of spur-towers guarding an important gate. Sometimes, as at Uronarti and Askut, the spur-walls were long and elaborate, and were used to occupy ground that could not be effectively enclosed but which could be used by an enemy to threaten the fort. The great permanent gates were protected by the barbicans, and others by smaller spurs, but some gates were simply breaks in the wall, presumably closed up during a siege. Fortresses without direct access to the river were often equipped with a stone-covered stairway to the water.
The interior of the fortress proper was almost completely filled with buildings, with only narrow passageways around the inside of the wall and streets providing communication. At Buhen, these streets were equipped with covered drains. Open squares were permitted to occupy only a small space. The plans of the buildings were rectilinear, even when the curtain had an irregular shape; only the buildings next to the outer wall were fitted to the shape of the wall. On irregular or sloping surfaces, the buildings might be terraced and the streets given rock-cut steps, as at Serra East, and some of the rooms were partly rock-cut. Magazines, some kind of headquarters building and granaries seem to have been the most common internal structures, but some may have been residences or offices. Military equipment, such as flint-tipped spears and leather shields, was manufactured in some of the forts. Evidence is incomplete because only the ground floors of the buildings are preserved.
A number of simple or exposed forts may have had no outbuildings, but the larger ones, such as Buhen and Mirgissa, and island forts, such as Uronarti and Askut, had residences, magazines and even substantial official buildings located close to the walls. These were sometimes protected by very strong outer fortifications, which at Aniba and Buhen greatly enlarged the protected area. Such outer fortifications, not tightly packed with buildings, were probably used as refuges in times of disturbance, or as staging areas for campaign operations. Simple, non-fortified enclosure walls found at Mirgissa and Semna South were probably for staging areas, trading camps or pens. The fortress complexes were not complete with these structures, for there were more distant residences and official buildings, such as the great slipway for transporting ships at Mirgissa, and even pottery kilns.
Two other types of structures associated with the forts remain enigmatic. The first consists of a circular basin sloped to a sunken pot or round depression in the center.
Draining into the basin are four rectangular slabs, each sloped to a channel. The second structure at Serra East consists of a roughly rectangular basin, circa 30x20m. Walls of irregular stones were sloped very much like an outer ditch built against a smooth, sloping surface of mudbrick, which continued over the parapet. No entry existed on the west side of this rectangular structure, so it was not a harbor, as was once thought. It was certainly important, for it occupies the fortress’s center, and it may have been used to confine captives.
The fortresses represent an immense allocation of resources. The walls of Serra East contained some 15,000m3 of mudbrick alone. For the entire complex, a truly major logistical effort must have been mounted, including the acquisition of large amounts of imported (?) timber, which was unavailable in the region. Each fort was built to sustain a siege by a well-organized opponent, and ritual architecture, consisting of small temples, was minimal. The great dry ditches were designed to obstruct tunneling, prevent combustibles from being piled against the walls, and fend off tanks, such as those shown in scenes in Middle Kingdom tombs at Beni Hasan, which covered sappers using poles to pry mudbricks from forts.
Administrative routine in the forts is reflected in the shreds of accounts, memoranda and dispatches that have been excavated, and there are numerous sealings for documents, chests and what were probably door-bolts. The door-bolt seals identify the main offices, most commonly the fort itself, the fortress granary, treasury, magazines and "Upper Fort" (Headquarters?). They were impressed in conical or shield-shaped mud lumps, placed over the bolt and cord which secured the door, and counter-stamped with the personal (scarab) seal of the officer on duty. Most of these stamps have no names or titles, with the audit trail assured by conical sample sealings kept on a string for reference. Where named, these officers were men of very moderate rank, mostly simple retainers. Only occasionally is there evidence of a seal of a high-ranking official, such as the southern vizier, usually from a document sent to the fortress. Seals from royal documents are rare and found only in a few fortresses.
Senusret III gave a general order for the southern frontier forts, to let no valley Nubian ("Nhsy") pass on land or on the river except to trade at Mirgissa. They might be fed, and "every good thing" done for them, but they had to leave the region. From the reign of Amenemhat III or slightly later, comes a papyrus, the Semna Dispatches, that vividly illustrates the measures taken to enforce this order, both against the valley Nubians and against the Medjay people of the Eastern Desert. It preserves eight somewhat fragmentary reports of contacts presented in a style familiar in modern military and police organizations, including the source of the report (Egyptians named, with forces described), persons encountered, their purpose, date and time, and action taken. The reports are signed by the reporting officer, with persons who received copies indicated, where appropriate. They were collected at Semna and forwarded to the office of the southern vizier at Thebes. Most of the contacts consisted of small parties (up to nine persons) of valley Nubians, including women, who arrived at Semna to trade. Their goods (not specified) were traded, and they returned southward by river the next morning. Three reports mention contacts with the Medjay. The dispatches reveal a policy of complete border control and careful reporting of all contacts, which contrasts with the relatively free access depicted in the tomb chapels of Middle Egypt less than a century earlier. Lower Nubia and Egypt were to be protected with a curtain of mudbrick fortresses, aggressive patrols and relentless administrators.
In the mid- and later eighteenth century BC, tombs and monuments of Egyptian officials and residents became common at some of the forts, especially Buhen. Other forts show signs of haphazard internal alterations, which reinforce the impression that those in the garrisons were becoming settlers, and an Egyptian village was built at Askut. Dating somewhat later, tombs and small cemeteries of the "Pan-grave" culture are found in Nubia and Upper Egypt, belonging to people from the Atbai region to the southeast, which demonstrate that the frontier no longer held back the Medjay. Still later, the fortress-populations fell under the control of the Kushite ruler, who was recognized as a pharaonic overlord by a commandant of Buhen. At Wadi es-Sebua on the east bank, Nubians themselves constructed a fort, a roughly circular enclosure of field stones, with the edge of the cliff forming its western side. Equipped with loopholes and three low, narrow gates, one of which was fortified, the entire structure was filled with huts and pens (?).
Most of the Egyptian fortresses were destroyed by fire some time after the Middle Kingdom. There is little stratigraphic evidence now to date this, but it seems unlikely that this destruction occurred when Lower Nubia came under Kushite control during the Second Intermediate Period. The forts were probably destroyed by the resurgent New Kingdom rulers, who followed an entirely different policy in Nubia by conquering it at least as far upriver as the Fourth Cataract, and perhaps even established posts beyond this point.
The New Kingdom was not the last time that forts in Nubia were built or renewed, for during the Napatan, Saite and Persian periods (beginning with the reign of the Kushite King Piye, circa 753 BC, to the conquest of Alexander, 332 BC), the frontier in Lower Nubia was again active. Although Roman forts built in northernmost Lower Nubia were part of the far-flung boundary complex of their empire, and the castles and fortified towns of later times (including Dabenarti near Mirgissa) were sometimes elaborate, none approached the systematic organization of the Egyptian Middle Kingdom boundary fortresses or the New Kingdom fortified towns.