The word derives from den (one) and has a primary meaning of "coming together," a "reunion" for the purpose of burial at the traditional tribal burial ground. It is the normal word for a popular assembly or gathering. It also occurs in place-names, meaning "a place of assembly."
The more elaborate burial mounds at an denach were associated with kings and kingship and were a focal point for the expression of identity of king and people. The references to social intercourse on such occasions, including horse racing, is reminiscent of the funeral games of the ancient Mediterranean world. By the seventh century, burial was for the most part in Christian graveyards, but the denach had become the assembly (still at the traditional site) of king and people on set occasions for the transaction of public business, with games, music, social interaction, and trade also part of the activities. The early Latin glosses on denach—theatrum and agon regale—are a further indication of this. The Latin circio (Hiberno-Latin for "circus") is also used for denach, as in the entry of the Annals of Ulster for the year 800 a.d. when the death of the local king is recorded at the fair, on the feast-day of St. MacCuilinn of Lusk (Co. Meath). The implication is that the denach was held at the local monastery. As local territories were incorporated into more powerful kingdoms, the political significance of these local den-achs declined, leaving only the social and commercial aspect intact. In this way the denach (Modern Irish aonach) survived as a "fair" into modern times.
There are references (dating between the eighth and twelfth centuries) to local fairs being held at churches such as Lusk, Armagh, Kildare, Glendalough, Lynally, Roscrea, Cashel, and Kells. The marketplace was marked with a cross in some of these sites. The word margad (market), from Old Norse markadr, itself from Latin mercatus, was probably borrowed into Irish during the tenth century. It glossed Latin nundinae, the market held every ninth day. It sometimes seems interchangeable with denach, and there are references to markets being held at the great provincial denachs held by the great kings, in which the political function was still of prime importance. Such was the Oenach Tailten, at Tailtiu (Telltown) situated on a loop of the river Blackwater in County Meath. This was the denach of the Ui Neill dynasty and was closely associated with Tara. In Leinster, Oenach Carmain was the main assembly of the Lein-stermen. Like Oenach Tailten, it was situated on a loop of the river Liffey in the parish of Carnalway, east of Kilcullen in County Kildare. Fairs such as these were sometimes not held or were disrupted for political reasons. The king who presided demonstrated his right to rule. A poem celebrating the Oen-ach Carmain provides most of what is known about these fairs. It was held on the feast of Lugnasad (August) every third year.
