The Japanese distributed opium among them and subjected some members of the community to human experiments, and combined with incidents of epidemic diseases this caused their population to decline until only 1,000 remained.[3][4][5][6][7] The Japanese banned Oroqen from communicating with other ethnicities, and forced them to hunt animals for them in exchange for rations and clothing which were sometimes insufficient for survival, which lead to deaths from starvation and exposure. Opium was distributed to Oroqen adults older than 18 as a means of control.