The Vikings raided across Europe, but took the most slaves in raids on the British Isles and in Eastern Europe. While the Vikings kept some slaves as servants, known as "thralls", they sold most captives in the Byzantine or Islamic markets. In the West, their target populations were primarily English, Irish, and Scottish, while in the East they were mainly Slavs. The Viking slave-trade slowly ended in the 11th century, as the Vikings settled in the European territories they had once raided. They converted serfs to Christianity and themselves merged with the local populace.