Brian's victory did have some real repercussions for Ireland. The Uí Néills had lost their stranglehold on the high kingship, and though they recovered it occasionally over the next 150 years, the title itself had lost most of its meaning. Without the Uí Néills in power, the leadership of Ireland was an open question, and many men were ready to take the job for themselves.

Economic changes in this period actually made warfare more dangerous. People were growing more food and producing more resources than they had in earlier centuries, and consequently the population was increasing. Lords required their growing populations to pay dues of live-stock and money, a situation similar to the feudal system in effect in England and Scotland. With the added resources and manpower, chiefs had the wherewithal to march farther afield and sustain longer campaigns, with accompanying higher fatalities.

To defend themselves, Irish lords built larger castles and fortifications. The kings of the provinces struggled against one another, but no one came out on top. Every time it looked as if one man would prevail, one of his so-called allies would do something treacherous and it would all come tumbling down.

By 1170, however, the question of an Irish high king was irrelevant; the Anglo-Normans had arrived, and from that point on Ireland's destiny was inextricably linked with that of the larger island to the east — England.