When did Japan started to take over Eastern Asia in World War 2?

You can begin with the late 1800's. At that time Japan, recently industrialized, began to seek colonies, just like the European nations and the USA. Until around 1950, all nations sought colonies since there was little 'free trade'. In order to purchase raw materials and have ready markets for industrial goods, the Europeans and Americans sought colonies. With few exceptions these colonies were economically pillaged by their masters. Locals were paid starvation wages for hard labor, prices were set low on the timber and ores taken from them (no competition meant that the English/French could pay whatever they wanted), and the industrial goods needed by the local population were in turn made very expensive. It was a great set up for the English/Dutch/Belgians/French (the most abusive four powers of this system), and made many of their citizens very wealthy. The Japanese began to expand by annexing Okinawa and surrounding islands. Shortly after they began to influence Korea. Then they moved into southern Manchuria. Manchuria was technically part of China but at that time China had an impotent central government. Many nations were taking pieces of China for themselves, often by taking over a coastal city, such as Macao or Hong Kong. This move into Manchuria put Japan into conflict with Russia. Russia was already in possession of a vast empire that included colonies in Poland, Finland, Lithuania, Armenia and many other places. Their never ending quest for expansion led them to northern China. Ultimately this led to the Russo-Japanese war. Japan destroyed the Russian naval forces sent from Europe. They also took the heavily fortified Russian outpost of Port Arthur in southern Manchuria. This defeat of Russia was the first time in recent human history that a non-European nation had defeated a European country. The victory greatly enhanced Japan's position in the Far East and allowed them to conclude the conquest of Korea and Manchuria. Using the industry and resources of Manchuria the Japanese built up a semi-autonomous army on continental Asia. This army began to make inroads into China proper, conquering various coastal areas, Peking, and Formosa. WWI ended in 1919 and Japan was given possession of Germany's extensive Pacific colonial empire, consisting of many islands, large and small. While the USA concluded its pacification of the Philipines in the 1920's (which killed an estimated 200,000 Philipino civilians), the Japanese continued to build their fleet, their Asian based army, to fortify the x-German islands, and make inroads into China. By the mid-1930's the China situation was full blown war with many attendant brutalities. These were extensively reported in American papers causing much hand wringing of those who increasingly saw Japan as a threat. As such the USA began to send aid, arms, and even pilots to China to assist their cause. When France fell to Germany in May/June 1940, Japan moved into Indochina, a French colony. This was done to block a southern supply route to their enemy, China. Clearly Japan was on a course that would ultimately lead to outright war with a major power - possibly Britain, Russia, or France - most likely the USA. The USA was the only nation with a sizable Far East fleet, based in Hawaii. The USA also had the large colony in the Philipines, which lay perfectly situated between Japan and the southeast Asian oil/timber/rice/tin resources needed by Japanese industry. When Germany concluded their vast victories in Europe against Russia, France, Netherlands and Britain the path was cleared for Japan to move against those countries colonies, now near defenseless. Wiping out the bulk of the American fleet in December 1941 at Hawaii enabled the Japanese to overrun all the colonies of the western nations from Burma to New Guinea, from the Philipines to Singapore. However, German reversals in Russia in December 1941 were not foreseen by the Japanese. This enabled Russia to stay in the war, thus encouraging Britain. Additionally, the USA public opinion was enraged by the concept of non-European peoples taking over colonies 'rightfully' owned by the USA, France, etc. A war of extermination was thus underway. The USA, with its much larger industrial base and vastly superior oil supplies, was able to outmanuever the Japanese over and over. Ultimately, the Japanese home islands were bombed into submission. Interestingly though, at the time of Japan's surrender they still controlled the bulk of their Asian conquests including most of China, Indonesia, Formosa, Thailand, Indochina and myriad small/medium size islands in the Pacific. All these were transferred to others an the conclusion of the fighting. Today, with the exception of Okinawa, the Japanese have relinquished all their holdings gathered since the nation first moved outward in the 1870's. The nation was demilitarized for the most part after WWII and placed under an American military 'umbrella'. This of course, meant that the USA has been obligated many times to protect the old Japanese empire from outsiders. This has led the USA into wars with Korea, China, and Vietnam. It is why the USA is heavily involved in nuclear talks with N Korea, despite the fact that N Korea is surrounded by huge military powers. Thus the residue of the once vast Japanese empire continues to filter down to us in the present.