Although Zambia, Malawi and Tanzania had achieved independence by the mid-1960s, the other nearby territories of Mozambique, Angola, Southern Rhodesia and South Africa were still under white minority control. Many activists from these territories moved to post-independence Lusaka, and American historian Evan Wade later described it as the "center of anti-colonial resistance for Southern Africa". In 1969, the city hosted the Fifth Summit Conference of East and Central African States, attended by fourteen leaders of African countries. The conference produced the Lusaka Manifesto, a pledge of solidarity by the signatories in seeking majority rule in southern Africa. The manifesto advocated a strategy of negotiation rather than violence and was later endorsed by the United Nations. The 1965 Universal Declaration of Independence in Southern Rhodesia and subsequent UN embargo and eventual border closure impacted Zambia's economy, depriving it of its principal trade route.