November 24, 2011
The hostage system
At the end of chapter 3 of Serpent of Time, Ryô rues becoming a "hostage." In medieval Japan, the exchange of "hostages" reached its apotheosis during Warring States period as a way of strengthening alliances between rival warlords.
Family members would take up residence in the castle of a rival to ensure against a double-cross or surprise attack. This meant, though, that things could get chancy for them if and when the alliance broke down.
Toyotomi Hideyoshi began systematizing the exchange of hostages during the late 16th century. The Tokugawa shogunate that followed converted it into a formal political institution known as sankin kôtai (参勤交代), or "alternate attendance."
Under sankin kôtai, provincial governors were required to spend every other year in the capital, and leave their wife and principal heirs behind when returning to their home territories.
Moving the seats of provincial government back and forth was a considerable undertaking. A Keynesian economist might point to the importance of sankin kôtai in maintaining Japan's heavily-trafficked coastal highways and inns.
However, the more Machiavellian purpose was to further weaken already overtaxed "outsider" clans by forcing them to make these massive expenditures, and to prevent them from concentrating their forces in one place.