According to Tibetan history books such as the `` Grand Ceremonies of the Wise `` , `` Chronicle of Tibetan Kings and Officials `` , and `` Chronicles of Tibetan Kings and Clansmen `` , there were believed to be a total of 35 tombs of Tibetan Kings and concubines from the 29th Tuboking to the last , divided into groups , with each group centred in a separate area in the Valley of Kings .