The Viking Age was a time of transition and upheaval in Scandinavia. Viking raiders returned to their homes with foreign slaves, new materials, and revolutionary ideas. Viking chieftains often converted to Christianity as a condition of peace agreements.
In the process, Norsemen changed -- sometimes violently -- not only the politics of those they met but also their own culture. In Scandinavia, Christianity began to replace traditional pagan religion, small farm production gave way to organized craft centers in places like York and Birka, and local areas gradually lost sovereignty to national kings. By the early 12th century, Scandinavian had become integrated into medieval, Christian European society, and descendants of Vikings who had settled abroad had little in common with their pagan ancestors.