Before their occupation by Japan.
I have often been fascinated by this question: why, if European institutions were so good, did the Asian colonies (e.g., Vietnam, Indonesia, Cambodia, India, Burma) experience an economic stagnation under European rule? Indeed, why, while Japan experienced mild per capita growth, did Japan’s colonies also experience economic stagnation while they were under Japanese rule? Why was European investment into the Asian colonies so low, with most European investment going to the 90%+ White world (Russia, U.S., Argentina, Australia, etc.)? The Asian colonies had the people in place to allow for quick economic transformation. Some (Vietnam, for instance) even had the human capital to do so on their own. And, yet, the Asian colonies in 1940 were barely improved from their state in 1840.
And why did it take until the end of imperialism for first-world countries to begin mass importations of Asian labor to cheapen domestic labor in cases where capital could not be invested overseas? Couldn’t the capitalists of that age understand the wisdom of importing foreign labor in order to cheapen the wages of domestic labor? Yes; in America, the 19th century import of Chinese labor was blocked due to labor union and White nationalist concerns in a democratic context. But did those concerns apply in, say, Germany, which was not even a democracy? Today, the White-majority countries automatically allow millions of legal Asian immigrants to flood into their country every year. Why didn’t that happen in the 19th or early 20th centuries, when the mutual gains from migration could have been almost as large?
If anything, this shows that political integration does not have to translate into either demographic or economic integration.