Yan Zhen was made the military governor of Shannan West Circuit in 782 and appeared to serve there until his death in 799, although the Jianzhong era ended in 783, so Zheng's service under Yan must have been in 782 and/or 783. See Old Book of Tang, vol. 117Archived May 8, 2009, at the Wayback Machine.
Yan Zhen was made the military governor of Shannan West Circuit in 782 and appeared to serve there until his death in 799, although the Jianzhong era ended in 783, so Zheng's service under Yan must have been in 782 and/or 783. See Old Book of Tang, vol. 117Archived May 8, 2009, at the Wayback Machine.