Tian Chengsi
Tian Huaijian was born in 802, during the reign of Emperor Dezong. Prior to his birth, his family had held Weibo Circuit for generations, ruling it in a "de facto" independent manner from the imperial regime, with his great-grandfather Tian Chengsi, Tian Chengsi's nephew Tian Yue, Tian Huaijian's grandfather Tian Xu, and father Tian Ji'an successively serving as the military governors ("Jiedushi") of Weibo. His mother was Tian Ji'an's wife Lady Yuan, a daughter of the general Yuan Yi (). He had least three brothers – Tian Huaili (), Tian Huaixun (), and Tian Huairang (), with the "Old Book of Tang" implying that he was older than his brothers and the "New Book of Tang" implying that he was younger than his brothers.