After the fall of the Roman Empire Europe went through a period of unrest and war known as the Dark ages from AD500 to 1000.
These hard times in Europe and the attacks from the Vikings forced many Monks to travel abroad to found monasteries throughout Europe. The Irish Monks abroad produced manuscripts in the Irish Style and worked to covert the rest of Europe into Christianity. This time was known as the Golden age.
Examples of some Irish Monks who helped in the golden age are:
St Columbanus
who was from Co. Down and founded several monasteries in Europe including Lixeuil in France and Bobbio in Italy.
St Colmcille
who was from Co. Derry and founded monasteries in an Island off the Scottish Coast. Including Iona where the Book of Kells was made.