Local leaders were obliged to provide troops, suppress local rebellions, and pay tribute to Beijing annually, biennially, or triennially according to their distance. The post was hereditary as opposed to the examination system in China proper, but succession, promotion, and demotion were all controlled by the Ming administration which required each "tusi" to use a seal and an official charter. To establish legitimate successions, "tusi" were ordered to list their sons and nephews in AD 1436, to redo the list in quadruplicate in 1441, and to renew the list triennially in 1441 and again in 1485. The Ming dynasty also took over regencies of children younger than 15 in 1489.