1.Leinster,Ulster,Munster and Connacht
2.Irish
3.Irish food and drink;Clean fresh air; Culture,music and dance
4.Irish monks
had a very important role in Medieval Europe,which they transformed culturally
In the sixth and seventh centuries,Irish monks established monastic institutions in parts of modern-day Scotland ,and on the continent,particularly in Gaul (especially Columbanus).Monks from Iona under St.Aidan founded the See of Lindisfarne in Anglo-Saxon Northumbria in 635,whence Celtic practice heavily influenced northern England.
reference（http://en.wikipedia.org/wiki/Celtic_Christianity）had a very important role in Medieval Europe,which they transformed culturally andspiritually.Britain,Scotland,France,Switzerland,Belgium,Austria,Italy,Slovakia,Russia,Iceland,Greenland,America...are in many ways linked to them.