China has come a long way since the ascenscion of the Qing Dynasty in the 19th century. The Chinese Empire has existed for centuries under various dynasties before the Western Powers began to deal with the East in the 19th century in more than just trade. The Empire originally refused trade with the Western Powers, and wished to be left alone, refusing to be in foreign relations with any nation. The United Kingdom defeated the Chinese Imperial Navy during the First Opium War, forcing the Nation to secede Hong Kong to the British.
After the Japanese defeated the Chinese in the Sino-Japanese War of 1860 and took Manchuria from the nation, the Chinese started to warm up to the Pre-Communalist states of Russia and Germany. The Germans aided the Chinese in Westernizing, much like the Japanese. As the Red Revolution began to overran the European states, China went into self-imposed isolation to curb the threat of Communalism in Asia.
When the Japanese War started in the 1910's, North Nippon invaded China via Communalist controlled Manchuria. Backed by British, Californian, American and Southern Japanese troops, the Chinese successfully drove the Communalist Japanese out of Northern China, but the war eventually ended in a stalemate, leaving Japan permanently divided at the 45th parallel. China later formed an alliance with the Japanese and joined the ATO in the late 1950's.