The Irish people are mainly of Celtic origin. The Celts arrived in the 5th century BC. They invaded Ireland along with Great Britain and other areas of Europe. In 432 AD St. Patrick arrived on the island and began to work to convert the locals to Christianity. Monasteries formed where Irish scholars studied Latin and Greek as well as developed the arts of manuscript, metalworking, and sculpture. The isolation of the monasteries helped keep this knowledge alive during the Dark Ages.