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In the 12th century, Ireland’s politics had changed into petty kingdom that only controlled a portion of a territory. As you can imagine, these small kingdoms were very unstable. In 1167, the Norman forces of King Henry II of England forced their way into England (encouraged by a former exiled Irish king, Diarmat Ma Murchada). Diarmait was able to gain some of his control back; but Henry was worried about his sovereignty over the Normans, and seized power again. Over the next hundred years, Norman power waned as the English kings regained control. This was beneficial to Irish families, as they were able to reclaim lost territory.