sentences:  From the 4th to the 11th century, the ancient kingdom of the Uí Fidgenti was approximately co-extensive with what is now County Limerick, with some of the easternmost part the domain of the Eóganacht Áine.The establishment of Limerick as a town and base by the Danes in the mid 900's, and their alliance with Irish families, including their alliance with Donnubán mac Cathail of the O'Donovans, resulted in significant conflicts with neighbouring clans, principally the O'Briens of Dál gCais, who raided into the Limerick area on a regular basis.The O'Briens retained their political power until late in the 1100s.