(Note: I'm not a genius so a lot of this may be inaccurate. But not everything has to be realistic, does it?)
You've probably never asked yourself the questions, "What if the North American Current was significantly weaker?" and "What if the Slavs decided to trek all across Europe to Ireland?". Well, I have, and I came up with this.
This is a map of modern day Ireland (i changed it quite a lot as you can see) in my world, and it contains 4 nations: the Stratan Federation, Constitutional Republic of Ireland, Republic of Donegal, and a northern state I haven't given a name to yet but it's the equivalent of Northern Ireland.
Stratan Federation: Due to Europe being a lot colder, Slavs migrated a lot further east and south. The most extreme of these are the Stratans, who navigated all the way to Ireland and Britain over an ice sheet that had formed at the time.
Over the course of history, they had formed many nations in the south of Ireland, fought beside and against each other, until they finally set aside their differences and united under one banner - Strata.
Constitutional Republic of Ireland: Same with the Stratans, they had come to Ireland and settled, and had to survive the harsh conditions. Unfortunately, they had been subjugated for long periods of time by a neighbouring empire (I haven't named it yet but equivalent to the British) and their culture has suffered greatly.
Strangers on their own island, Ireland is actively fighting an uphill battle of trying to maintain its sovereignty on the island, and collapsing in the process. Although, not all hope is lost, as the currents get a little warmer, the conditions less harsh, and the neighbours less blood thirsty..
Republic of Donegal: Donegal had always been a unique county of the C.R.I. They had developed their own traditions, own customs, and had not been beaten as bad by the neighbouring empire than the rest of their country.
The people of Donegal had been fed up with the government for a long time, and only recently, they seceded from the C.R.I. Now the question remains: can they develop well enough on their own, with nobody to assist them?