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Before their abolition in 1871, Japan was divided into domains known as han although there's considerable evidence to suggest that this term was only used from the early 18th Century onwards. Each domain was led by a daimyo. Daimyos could truly or nominally be appointed as the head of the domain by the bakufu, the shogunal Tokugawa government. There were plenty of incidences when disloyal/incompetent/politically dangerous daimyo were removed and replaced by the shogunate. Domains was required to pay a certain tax based on their koku ratings: rice production. Furthermore, the vast majority of domains had to make a trip to the shogunate's capital, Edo, on a regular basis, bearing gifts, which drained the domains' economy significantly. That was a major reason for doing this; it kept the domains weak in case of a rebellion.

However, domains were nevertheless surprisingly independent. Most domains had their own currency, and because the government severely restricted the movement of commoners from domain to domain, regionalism flourished. It could almost be said that the domains were separate countries.

This sort of Japan was rapidly and radically changed after the Meiji Restoration however. The Meiji "Founding Fathers" pursued centralization based on Western examples. However, I believe that a federation would not have been overly out of place. Perhaps if the new leadership had followed the American example, Japan could have been made into a "Federal Empire" with "states" rather than "prefectures." Such a Japan could have had a very different history to the OT Empire of Japan. What do you think?
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