This vicariate, entrusted to the Missions Étrangères of Paris, comprised all the territory included in British (Lower) Burma before the annexation of Upper Burma, except the province of Arakan (attached in 1879 to the Diocese of Dacca) and the Toungoo district (assigned to the above Vicariate of Eastern Burma). It is bounded on the east by the Diocese of Dacca, on the north by Eastern Burma, on the west by Siam and on the south by the sea. It extends from the nineteenth to the tenth parallel of north latitude and beginning from Moulmein, forms a long and rather narrow strip of land shut in between Siam on the one side and the sea on the other.