 The residence of the prefect Apostolic was the mission of St. Joseph de Luluabourg, situated a few miles to the south of the station of the Belgian colony of Luluabourg (now Kananga), in the district of Lualaba-Kassai, the chief town of which was Lusambo, residence of the district commissioner.The prefecture, at the time of its creation, comprised almost all the Lualaba-Kassai district.It was bounded on the north by the Vicariate of Belgian Congo (district of the Equateur); on the east by the same vicariate (territory of the Katanga Company); on the south by Portuguese Congo; on the west by the Lubue River.