Discussion on defining district borders for Tokyo is in progress. If you know the city pretty well, please share your opinion on the talk page.
Over 500 years old, the city of Tokyo grew from the modest fishing village of Edo (江戸). The city only truly began to grow when it became the seat of the Tokugawa shogunate in 1603. While the emperor ruled in name from Kyoto, the true power was concentrated in the hands of the Tokugawa shogun in Edo. After the Meiji restoration in 1868, during which the Tokugawa family lost its influence, the emperor and the imperial family moved here from Kyoto, and the city was re-named to its current name, Tokyo. The metropolitan center of the country, Tokyo is the destination for business, education, modern culture, and government. (That's not to say that rivals such as Osaka won't dispute those claims.)