Sino-Japanese relations - i.e. interstate relations between the People's Republic of China and Japan - have a long and complicated history. China for centuries was considered the "big brother" of Japan , influencing Japan through the writing system, architecture, philosophy, and religion. This influence though did not translate into political and economic interaction, until the Western industrial civilization pushed into the East in the 19th century.

The Westerners were looking to trade with an East Asian society, but China was very resistant to foreign impact on its civilization. In sharp contrast, Japan was much more willing to comply and realized the benefits in the West's technical and social development. Japan 's course of actions reversed the relationship between Japan and China , now China would soon look upon Japan for modernizations.

This change of supremacy caused aggression between Japan and China , starting with Japan 's annexation of the Ryukyu Islands, over the annexation of Taiwan after the Sino-Japanese war of 1894, to the declaration of war on China in 1937. Japan was soon able to gain control over all Chinese outlying territories.