Its limits, as fixed on December 10, 1895, were:[1][2] This district was originally included in the Apostolic Vicariate of Tanganyika.

Ganachan of the White Fathers penetrated this previously unknown region and endeavoured to settle at Tabora, but was unsuccessful.

Guillet succeeded and opened an orphanage there, which was shortly afterwards transferred to Kipalapala one league distant.

A German scientist, Dr. Richard Kandt, a Protestant, was so impressed by the good work of the Catholic missionaries that he presented his estate at Tabora to the vicar Apostolic to found a school and hospital.

The first vicar Apostolic, Mgr François Gerboin, of the White Fathers, born in 1847 and consecrated titular Bishop of Turbubto in 1897, resided at Ushirombo.