Dugu Sun
He was killed in a purge of high-level Tang officials by the warlord Zhu Quanzhong the military governor ( "Jiedushi" ) of Xuanwu Circuit ( 宣武 , headquartered in modern Kaifeng , Henan ) , who was then preparing to seize the throne . 
<triplet> Kaifeng <subj> Henan <obj> located in the administrative territorial entity <triplet> Henan <subj> Kaifeng <obj> contains administrative territorial entity