Excerpts from Books and Wikipedia
"The Battle of Sekigahara was a decisive battle on October 21, 1600 that preceded the establishment of the Tokugawa shogunate. Tokugawa Ieyasu took three more years to consolidate his position of power over the Toyotomi clan and the daimyōs, but Sekigahara is widely considered to be the unofficial beginning of the Tokugawa bakufu, the last shogunate to control Japan." [Wikipedia] "The Himeji castle at Hyogo in western Honshu was the base for Toyotomi Hideyoshi's campaign to unify Japan in the 1570s and 1580s. Japan's network of regional power bases, often centered on castles, was viewed as a threat to control and unity by Hideyoshi and his successor, Tokugawa Ieyasu, who founded the Tokugawa shogunate in 1603. Both leaders aimed to reduce regional power by destroying local strongholds and prohibiting the use of arms by merchants, monks, and farmers. In addition, a policy of shi-no-ko-sho froze class distinctions, rigidly separating Japanese society into warriors, farmers, artisans, and tradesmen. The samurai, or warrior class, were based at castle towns, such as Hyogo, where they became bureaucrats." [DK timelines, p. 290]