Not a lot of people know this, but chess goes back a long way with the Irish. The Irish equivalent of King Arthur and the Knights of the Round Table were Fionn MacCumhaill ( pronounced Feeyun MacCool) and the Fianna. Each of these warriors was expected to perfect his chess as much as his swordplay, as many disputes were settled by a game of chess rather than by violence. Fionn frequently was caught in situations where his chess came in very handy, though if that didn't fix it, he was perfectly capable of seeing off his enemies in a more bloody fashion. The Fianna supposedly flourished shortly after the time of Jesus Christ, so the game must have entered the Irish psyche even earlier.
The Celtic languages of Ireland, Scotland, Wales, Cornwall and Britanny, in North-Western France, belong to the Indo-European group of languages, so this may explain how a game with its roots in India had found its way to the outermost settlements of Europe by the beginning of the Christian era.
Chess was also popular with the fairies (not leipreachans) of Ireland, as they frequently used it to trap mortals into selling their souls.
So, with that headstart, why are the Irish so weak at the game now? If only FIDE would allow fairies into the World Championship!