Several major refugee movements have been caused by territorial partition. After the defeat of Germany in World War II, for example, the Potsdam Conference of 1945 authorized the transfer of German minorities from a number of European countries, and 12,000,000 Germans were dumped on the territory of Germany, which was split into east and west regions. The disintegration of the European colonial empires also brought about the return of thousands of British subjects from all parts of Africa and Asia, of French refugees from North Africa and Indochina, of Italians from Libya, and of the Dutch from Indonesia. Since the 1960s large concentrations of refugees have been located in Africa and Asia. Black Africa's peoples had moved freely within their tribal areas for centuries, but, with the emergence of sovereign African states beginning in the 1950s, national boundaries became barriers to population movements. As a result of internal and external power struggles, as well as tribal hostility within these new states, the number of refugees in Africa increased from 860,000 in 1968 to 6,775,000 by 1992. During the 1980s and early 1990s, the principal source of the world's refugees was Afghanistan, where the Afghan War (1978-1992) caused more than 6,000,000 refugees to flee to Pakistan and Iran. Iran also provided asylum for 1,400,000 Iraqi refugees who had been uprooted as a result of the Persian Gulf War (1990-1991). Beginning in 1991, political upheavals in Europe produced significant population movements. The breakup of Yugoslavia, for example, displaced some 2,000,000 people by mid-1992.