Botswana is a land-locked country in Southern Africa, 70 percent of the land being Kalahari Desert, but also boasting the UNESCO World Heritage site of the Okavango Delta famous for its wildlife, and also for the latest theory of the origin of Anatomically Modern Humans (AMH). With a current population of just over 2,300,000, Botswana is Africa's oldest continuous democracy and one of the continent's most stable and increasingly prosperous nations. Diamonds contribute to Botswana's economy. The former Kingdom of Bechuanaland, a British Protectorate from 1885 to independence in 1966, is famous for the romantic love-match between Seretse Khama, heir to the throne of Bechuanaland and his wife, former London typist Ruth Williams, and also the crime fiction by Alexander McCall Smith relating the investigations of the No.1 Ladies' Detective Agency.