British-administered mandate (from 1946 a UN trust territory) covering mainland German East Africa after WWI; the League of Nations formally conferred the Class B mandate on Britain on 20 July 1922.
Became independent as Tanganyika on 9 December 1961 (a republic within the Commonwealth from December 1962), then united with the People's Republic of Zanzibar on 26 April 1964 to form Tanzania.
The standard scholarly history of the territory, covering German conquest through the British mandate/trusteeship era to independence — squarely this polity's span.