Birka (Birca in medieval sources), on the island of Björkö (lit. "Birch Island") in present-day Sweden, was an important Viking Age trading center which handled goods from Scandinavia as well as many parts of Continental Europe and the Orient. Björkö is located in Lake Mälaren, 30 kilometers west of contemporary Stockholm, in the municipality of Ekerö.
Birka was founded around AD 750 and it flourished for more than 200 years. It was abandoned c. AD 975, around the same time Sigtuna was founded as a Christian town some 35 km to the northeast. It has been estimated that the population in Viking Age Birka was between 500 and 1000 people.