Zanzibar ; Tanganyika ' s President Julius Nyerere ( right ) bids farewell to Zanzibar President Abeid Karume as the former left Zanzibar Airport on the 22nd April , after both had signed an agreement which merged their two coountries into " one sovereign state " . The agreement , believed to be the first step by the two Presidents to prevent Zanzibatr becoming another Cuba , concluded a sudden two - hour visit by Nyerere to the island Republic . It is reported that Nyerere will head the new state , which has been given the new name of " Tanzan " in the locval press . 25 April 1964