Shown left, the territoies inhabbited by the principal clans of of the DalgCais. The Ui Caisin were known to have held sway over Magh Adhair (The plain of Adhar) from the fifth centiruy AD through to the fourteenth century when they expelled the neighbouring Ui Bloid clan from Tradree. Eventually they pushed Ui Bloid out of easstern Thomond almost completely. By the end of the Thomond wars in 1318 The Clan MacNamara held the territories of Ui Caisin, Tradree and Clan Cuilean.
Ireland from around the fourth century was broken into four major provinces, each being made up of small kingdoms inhabbited by the celtic tribes. The Dal gCais established the Kingdom of Thomond in what, today is known as County Clare. From there the Dal gCasi ruled over the province of Munster. While the knigdoms within each province often fought amougst themselves it was not uncommon for them to band together in fragile alliances to wage war against a neighbouring province.
The Vikings provided the first real threat to Celtic Ireland. Raiding in small numbers at first, they had by 950AD established variours settlements providing the basis for modern cities in Ireland today. Whislt effective in warfare the Irish began to adapt develope new guerilla like tactics to deal with the Viking invaders. The viking expansion was eventually halted when Brian Boru and his forces defeated the Vikings at the Battle of Clontarf in 1014AD.Whilst putting an end to Viking expansion, Clontarf did not extinguish the trading settlements that had been established over the preiouse two centuries.