Prime Minister of Rhodesia held the post until the end of Federation on 31 December 1963. When Northern Rhodesia gained independence as Zambia on 24 October 1964, Southern Rhodesia began to refer to itself simply as "Rhodesia". Prime Minister Ian Smith's government issued a Unilateral Declaration of Independence from Britain in 1965, and he remained Prime Minister when the country was declared a republic in 1970. Under the Internal Settlement in 1979, after a long period of conflict, the country became known as Zimbabwe-Rhodesia, with Abel Muzorewa as its first black Prime Minister. None of these acts were recognised internationally, and under the Lancaster
Southern Rhodesia Treaty, which was signed by King Lobengula of the Ndebele people. "Southern" was first used in 1898 and dropped from normal usage in 1964, on the break-up of the Federation of Rhodesia and Nyasaland. "Rhodesia" then remained the name of the country until the creation of Zimbabwe Rhodesia in 1979. Legally, from the British perspective, the name Southern Rhodesia continued to be used until 18 April 1980, when the Republic of Zimbabwe was promulgated. The British government agreed that Rhodes' company, the British South Africa Company (BSAC), would administer the territory stretching from the Limpopo to Lake Tanganyika under charter