Ministry. Initially based in Truk, the Civil Affairs Bureau was moved to Koror in the Palau islands in 1921. The naval garrisons were disbanded to comply with the terms of the Mandate. In April 1922 a civilian government was established in each of the six administrative districts (Saipan, Palau, Yap, Truk, Ponape and Jaluit) in the form of a civil administration department which still reported to the local naval garrison commander. At the same time a post of Governor of the South Seas Mandate was created. Governors were mostly admirals or vice-admirals as the administration was initially still the responsibility of the IJN. The Governor reported directly to the Prime Minister of Japan. After the establishment of the Ministry of Colonial Affairs in June 1929, the Governor reported to the Minister of Colonial Affairs instead. The establishment of the "South Seas Government" or "Nan'yo-Cho" in March 1932 finally put the government of the islands under a purely civilian administration. When the Ministry of Colonial Affairs was absorbed into the Ministry of Greater East Asia in November 1942, the primacy of the IJN was again recognized by the appointment of an admiral as the Governor. Furthermore, the six administrative districts were reduced to three in November 1943: North, East, and West. Significance The population of the South Seas Mandate was too small to provide significant markets and the indigenous people had very limited financial resources for the purchase of imported goods. The major significance of the territory to the Empire of Japan was its strategic location, which dominated sea lanes across the Pacific Ocean and provided convenient provisioning locations for sailing vessels in need of water, fresh fruit, vegetables and meat. As a signatory of the 1922 Washington Naval Treaty, Japan agreed not to build new naval and air stations on the islands and it did not begin direct military preparations in the Mandate until the late 1930s. Nevertheless, the territory provided important coaling stations for steam-powered vessels and its possession gave an impetus to the Nanshin-ron doctrine of "southward advance". Population The population of the islands increased during the period of the mandate as a result of Japanese settlement in Micronesia. Settlers were initially drawn from Okinawa Island and the other Ryukyu Islands, but immigrants subsequently came from other parts of Japan, particularly the economically deprived Tōhoku region. Agricultural workers were followed by shopkeepers, restaurant, geisha house and brothel-keepers, expanding