In the Pingfang area, 20 kilometers south of Harbin, the Japanese established a "special military zone," which served as head-quarters for germ warfare. This was called "the quarantine and water supply department" of the Japanese expeditionary force in Manchuria or Manchurian 731 unit.
次年，日本又在哈爾濱以南廿公里的「平房」，設定「特別軍事地域」，驅逐該地區所有的老百姓後，大興土木，建設準備完成，便將其從事細菌戰的本部﹘ ﹘滿洲第七三一部隊，也就是日本精銳關東軍的極秘密部隊，對外的掩護是「關東軍防疫給水部」﹘﹘遷至平房。