The name of the country is derived from the Namib Desert, considered to be the oldest desert in the world. Namibia, officially the Republic of Namibia, is a country in southern Africa whose western border is the Atlantic Ocean. It shares land borders with Angola and Zambia to the north, Botswana to the east and South Africa to the south and east. Although it does not border with Zimbabwe, less than 200 metres of riverbed (essentially the Zambia/Botswana border) separates them at their closest points. Area: 824,292 km² (318,260 sq. mi.) It gained independence from South Africa on 21 March 1990, following the Namibian War of Independence. Its capital and largest city is Windhoek. Namibia is a member state of the United Nations (UN), the Southern African Development Community (SADC), the African Union (AU), and the Commonwealth of Nations.