The discovery of the remains of the Australopithecus hominid family in Tanzania's Olduvai Gorge supports claims that this region gave birth to humanity. About 3,000 years ago Khoisan peoples entered the region, followed by caucasoid Cushites and Negroid Nilotes from the north. As long as 2000 years ago traders from Egypt (Greeks and Romans), Axum (Ethiopians), Arabia, the Persian Gulf, India and Indo nesia visited the shores and around 500 AD the Bantu-speaking peoples moved in from the great lakes. Portuguese explorers reached the coastal regions in 1500 and held some control until the 17th Century. Most strongholds established by the Portuguese fell into Arab hands by the early 19th Century. In 1840 Sayyid Said, the Imam of Muscat (Oman), took up residence on Zanzibar Island and established a sultanate that spanned over the entire coastal belt and associated islands of present-day Tanzania and Kenya. Homegrown spices, slaves, and ivory from the mainland were traded in Zanzibar, which eventually became a base from where the likes of Livingstone and Stanley explored. In 1871 American journalist Henry Stanley went from Zanzibar to look for Livingstone and found him at the slave depot of Ujiji (close to Kigoma) on Lake Tanganyika, using the memorable phrase, "Dr. Livingstone, I presume?" A German East African Protectorate formed in 1891 included Tanganyika and its coastal belt (formerly part of the Zanzibar Sultanate), as well as the kingdoms of Ruanda and Rundi. After Germany's defeat in World War I, Tanganyika was handed over to Britain and Ruanda-Urundi to Belgium. The Zanzibar Protectorate remained a separate sultanate under British rule. Julius Nyerere and his Tanganyika African National Union (TANU) gained independence for Tanganyika in 1961. Three years later it joined with Zanzibar in the United Republic of Tanzania and Zanzibar. Over the next 30 years Nyerere's socialist communes (ujaama) led to economic disaster. In 1984 he was succeeded by his vice president, Ali Hassan Mwinyi, who introduced some changes and in 1995 newly-elected President Benjamin Mkapa set Tanzania firmly on the road to reform. In October 2000 Mkapa was reelected by 71.7% of the popular vote over his nearest rival, Ibrahim Lipumba. In 2005, Jakaya Mrisho Kikwete was elected as his successor. Like his predecessors, Kikwete is a member of the ruling Chama Cha Mapinduzi (CCM) party.