the yonggu mausoleum () is the mausoleum of empress feng (442-490), formally empress wenming and the wife of emperor wencheng of the northern wei dynasty of chinese history. the tomb is located on a mountain about 25 kilometers from the city of datong, in shanxi province. when her husband died in 465, empress dowager wenming became regent until her stepson, emperor xiaowen, attained his adulthood. while emperor xiaowen assumed the imperial powers upon adulthood, she remained highly influential until her death in 490. this was at the time buddhism became a state religion and empress dowager wenming was responsible for the imperial shrines at yungang grottoes. there is evidence that the empress dowager wenming masterminded the transformation of the government and the sinification movement.