Originally the Tanzanian Rugby Football Union was incorporated into the Rugby Football Union of East Africa (RFUEA) in 1956. This tended to be dominated by Kenya, but Tanzania got its own union in the 1970s.
Tanzanian rugby was for a long while subsumed under "East Africa", which tended to be dominated by Kenya. The game is established in the former Tanganyika, but not Zanzibar, despite attempts to help get the game established there.
For many years rugby in East Africa was dominated by whites and expatriates, In Kenya and Uganda the game was readily taken up by the indigenous black community in the early 1970s though in Tanzania black players still make up a minority of the sport's participants there are several initiatives to change this.