Sankin-kōtai

Sankin-kōtai (Japanese: 参覲交代/参覲交替, now commonly written as 参勤交代/参勤交替, 'alternate attendance') was a policy of the Tokugawa shogunate during most of the Edo period, created to control the daimyo, the feudal lords of Japan, politically, and to keep them from attempting to overthrow the regime.

The cost of maintaining several lavish residences as well as the journeys to and from Edo was a constant drain on the finances of the daimyo, which greatly increased the shogunate's control over them and kept them militarily weak.

Toyotomi Hideyoshi had earlier established a similar practice of requiring his feudal lords to keep their wives and heirs at Osaka Castle or the nearby vicinity as hostages to ensure their loyalty.

Modern scholars have been unable to confirm the existence of such detailed rules, but there is evidence that, at least in principle, Kamakura period gokenin owed some kind of service at the shogun's court.

[5] These obligations on the Kamakura gokenin had a limiting effect on local independence, like the more rigid sankin-kōtai system that emerged in the Edo period.

Shimmi Kichiji claimed that the prolonged absence of the gokenin from their fiefs due to their obligatory attendance at the capital delayed the development of true feudalism in Japan.

[6] The details changed throughout the 26 decades of Tokugawa rule, but generally, the requirement was that the daimyōs of every han move periodically between Edo and his fief, typically spending alternate years in each place.

With hundreds of daimyōs entering or leaving Edo each year, processions (大名行列, daimyō-gyōretsu) were almost daily occurrences in the shogunal capital.

The nobles were expected to assist the king in his daily duties and state and personal functions, including meals, parties, and, for the privileged, rising from and getting into bed, bathing, and going to church.