Botswana , officially the Republic of Botswana (Setswana: Lefatshe la Botswana; Kalanga: Hango yeBotswana), is a landlocked country in Southern Africa. Botswana is topographically flat, with up to 70 percent of its territory being the Kalahari Desert. It is bordered by South Africa to the south and southeast, Namibia to the west and north, and Zimbabwe to the northeast. It it connected to Zambia across the short Zambezi River border by the Kazungula Bridge. A mid-sized country of slightly over 2.3 million people , it is one of the most sparsely populated countries in the world. About 11.6 percent of the population lives in the capital and largest city, Gaborone. Formerly one of the world’s poorest countries—with a GDP per capita of about US$70 per year in the late 1960s—Botswana has since transformed itself into an upper middle income country, with one of the world’s fastest-growing economies. Homo sapiens had first inhabited the country over 200,000 years ago. The Tswana ethnic group were descended mainly from Bantu-speaking tribes who migrated southward of Africa to modern Botswana around 600 AD, living in tribal enclaves as farmers and herders. In 1885, the British colonized the area and declared a protectorate under the name of Bechuanaland. As decolonization occurred, Bechuanaland became an independent Commonwealth republic under its current name on 30 September 1966. Since then, it has been a representative republic, with a consistent record of uninterrupted democratic elections and the lowest perceived corruption ranking in Africa since at least 1998. The economy is dominated by mining, cattle, and tourism. Botswana has a GDP (purchasing power parity) per capita of about $18,825 per year as of 2015 , one of the highest in Africa. Its high gross national income (by some estimates the fourth-largest in Africa) gives the country a relatively high standard of living and the highest Human Development Index of continental Sub-Saharan Africa.