 Leinster, once a much larger region, the northern parts of which had been conquered by the Uí Néill, was the target of expansionist Uí Néill kings, and also of the Eóganachta.The contest for control of Leinster would play a major part in Cathal's reign, and indeed in relations between the Eóganachta and Uí Néill in the centuries which followed.The kings of Connacht claimed a common kinship with the Uí Néill, and were largely favourable towards them.