The very first modern humans are believed to have inhabited South Africa more than 100,000 years ago. In 1999, Unesco designated the region the Cradle of Humankind World Heritage site. South Africa's first known inhabitants have been referred to as the Khoisan, the Khoekhoe and the San. Starting in about 1,000 BCE, these groups were then joined by people who migrated from Western and Central Africa during what is known as the Bantu expansion southwards through Africa. European exploration of the African coast began in the 13th century when Portugal sought an alternative route to the silk road to China. In the 14th and 15th century, Portuguese explorers traveled down the west African Coast, detailing and mapping the coastline and in 1488 they rounded the Cape of Good Hope. The Dutch East India Company established a trading post in Cape Town under the command of Jan van Riebeeck in 1652, European workers who settled at the Cape became known as the Free Burghers and gradually established farms in the Dutch Cape Colony. Following the Invasion of the Cape Colony by the British in 1795 and 1806, mass migrations collectively known as the Great Trek occurred during which the Voortrekkers established several Boer settlements on the interior of South Africa. The discoveries of diamonds and gold in the nineteenth century had a profound effect on the fortunes of the region, propelling it onto the world stage and introducing a shift away from an exclusively agrarian-based economy towards industrialisation and the development of urban infrastructure. The discoveries also led to new conflicts culminating in open warfare between the Boer settlers and the British Empire, fought essentially for control over the nascent South African mining industry. Following the defeat of the Boers in the Anglo–Boer or South African War (1899–1902), the Union of South Africa was created as a self-governing dominion of the British Empire on 31 May 1910 in terms of the South Africa Act 1909, which amalgamated the four previously separate British colonies: Cape Colony, Colony of Natal, Transvaal Colony, and Orange River Colony.