A country of northwest Europe on the North Sea. Inhabited by Germanic tribes during Roman times, the region passed to the Franks (4th–8th century), the Holy Roman Empire (10th century), the dukes of Burgundy (14th–15th century), and then to the house of Habsburg. The northern part of the region formed the Union of Utrecht in 1579 and achieved its independence as the United Provinces in 1648 after the Thirty Years' War. In the 17th century the country enjoyed great commercial prosperity and expanded its territories in the East and West Indies and elsewhere. The kingdom of the Netherlands, proclaimed at the Congress of Vienna (1814–1815), included Belgium until 1830. Amsterdam is the constitutional capital and the largest city; The Hague is the seat of government.