 In 1941 China's first animated feature film of notable length, "Princess Iron Fan", was released under very difficult conditions during Second Sino-Japanese War and World War II using extensive rotoscoping.While there were overlapping progress made in the Asian regions with Japanese anime at the time, they were not geographically or artistically influential to China directly.During the Japanese invasion period, the brothers produced more than 20 animated propaganda shorts focusing on various patriotic topics from resistance against Japanese troops, opium and imperialism.