An evolution had taken place in the centuries from the time of the Kamakura bakufu, which exists in equilibrium with the imperial court, to the Tokugawa, when the bushi becomes the unchallenged rulers in what historian Edwin O. Reischauer has called a ''centralized feudal" form of government.

Instrumental in the rise of the new bakufu is Tokugawa Ieyasu, the main beneficiary of the achievements of Nobunaga and Hideyoshi.

Already powerful, Ieyasu profits by his transfer to the rich Kanto area.

He maintains two and a half million koku of land, has a new headquarters at Edo, a strategically situated castle town (the future Tokyo), and has an additional two million koku of land and thirty-eight vassals under his control.

After Hideyoshi 's death, Ieyasu moves quickly to seize control from the Toyotomi family.