The first modern humans are believed to have inhabited South Africa more than 100,000 years ago. South Africa's prehistory has been divided into two phases based on broad patterns of technology namely the stone age and iron age. After the discovery of hominins at Taung and australopithecine fossils in limestone caves at Sterkfontein, Swartkrans, and Kromdraai these areas were collectively designated a World Heritage site. The first inhabitants of South Africa are collectively referred to as the Khoisan, the Khoi Khoi and the San separately. These groups were displaced or sometimes absorbed by migrating Africans (Bantus) during the Bantu expansion from Western and Central Africa. While some maintained separateness, others were grouped into a category known as Coloureds, a multiracial ethnic group which includes people with shared ancestry from two or more of these groups: Khoisan, Bantu, English, Afrikaners, Austronesians, East Asians and South Asians. European exploration of the African coast began in the 13th century when Portugal committed itself to discover an alternative route to the silk road that would lead 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.