The POD here is that Brian Boru is never killed and becomes the High King of all Ireland. Meanwhile in Britain, the Normans never invade.
1014: Battle of Clontarf won! Brian Boru is crowned as the high king. He builds up Eire's army.
1015: Ireland invades Wales. Brian has the hope of making an empire. They meet fierce resistance, but the Irish are more organised.
1016: Wales falls to Ireland. Brian sets his eyes on Scotland and so, the invasion of Scotland begins. Fierce resistance from Vikings make this invasion tougher, but the Irish win.
1017: Brian sends wise people to other country's in Europe to gather info and other things. Like, new armour, new military tactics, etc. They come back and the Irish Army improves a lot. Ireland has lots of knights.
1018: Brian proposes the idea of a Celtic-Saxon empire to the Saxons to beat the Vikings. They accept and a powerful empire is created. The Celtic-Saxon Empire! They beat the Vikings.
1019: The Empire sends explorers to discover new places. They land in America and make peace with the natives. The natives agree to join them. Celtic-Saxon colonies are set up and the natives intermarry with them.
1020: The empire goes to South America, Central America and Africa. They make peace with the natives and once again, the native intermarry with them.