The Ōshū Fujiwara grew rich on northern gold, the fourth lord turned on the fugitive his father told him to protect, his own vassal beheaded him, and his head lies in the family's gold hall

The Ōshū Fujiwara ruled northern Japan from Hiraizumi for four generations. A 2021 study in PLoS ONE says the region exported horses and gold, and its lords used gold to buy influence in the capital. In 1124 they finished the Konjiki-dō at Chūson-ji, a small hall covered inside and out in gold leaf. The third lord, Hidehira, sheltered Minamoto no Yoshitsune, who was wanted by his brother Yoritomo. Hidehira died on 30 November 1187, aged about 65. He reportedly asked his son Yasuhira to keep supporting Yoshitsune. In 1189 Yasuhira attacked Yoshitsune instead. Yoshitsune killed himself, and Yasuhira sent his head to Yoritomo. Yoritomo marched on Hiraizumi anyway. Yasuhira set fire to his city and fled north, and one of his own vassals beheaded him. The record says an iron nail was driven through his head. The head was later put in a lidded bucket in the Konjiki-dō, beside the mummified bodies of his father, grandfather and great-grandfather. A 1950 examination found a sword wound and holes in the skull and a cut on the neck. It also found about 100 lotus seeds in the head's container. A researcher germinated them in 1995, and the lotus now flowers at Chūson-ji. The hall became part of a UNESCO World Heritage site in 2011. The mummies remain under its altars and are closed to new research.