The region now known as Guinea-Bissau has been inhabited for thousands of years. In the 13th century, it became a province of the Mali Empire that later became independent as the Empire of Kaabu. The region was claimed by Portugal beginning in the 1450s. During most of this period, Portuguese control of the region was limited to a number of forts along the coast. Portugal gained full control of the mainland after the pacification campaigns of 1912–15. The offshore Bijago islands were not colonised until 1936. After independence in 1974, the country was controlled by a single-party system until 1991. The introduction of multi-party politics in 1991, brought the first multi-party elections in 1994. A civil war broke out from 1998 to 1999.