Kenya is home to some of the rarest and most interesting species of wildlife in the world. Because of this, tourism is one of the country’s major sources of foreign exchange, with visitors coming largely from countries of the European Union. Tourism revolves around a basic framework of national parks, game reserves, and game sanctuaries, where a wide variety of animals and cultural attractions can be enjoyed. The number of tourists began to vary annually in the early 1990s, however, following a period of political unrest and attacks on tourists, and again in the early 2000s, owing partially to the threat of terrorism.