后仇池
(?
386年～
395年)
杨定（？－394年）是中国东晋时期的仇池首领之一。
杨定是前秦主苻坚之婿，也是前秦的一位骁将，在西燕军进逼长安时，定曾大破慕容冲军。385年五月，
杨定被慕容冲俘虏，苻坚大惧，留太子守长安，自己带数百骑及一些家人出走五将山。苻坚死后的385年十月，西燕军五万人在新平（今陕西彬县）南被后秦击败，主帅高盖降秦，
杨定趁机逃到陇右，收集旧部，重振仇池。
杨定一直在名义上归顺前秦，接受前秦授予的官爵，曾经出兵协助前秦对抗后秦。他又先后自称龙骧将军、仇池公、秦州牧、陇西王，并且遣使向东晋称藩。
394年十月，前秦末主苻崇被陇西鲜卑的乞伏干归（后来的西秦王）驱逐，逃到
杨定那里。
杨定率领二万人与苻崇共攻干归，先胜后大败，定及崇俱被杀。
杨定无子，其堂兄弟杨盛自称仇池公，谥
杨定为武王。
Yang is scheduled to Former Qin Emperor Fu Jian of the husband, is one of the Former Qin Xiao Qiang, YAN Jun advancing in the West Chang An, the set had broken Murong Chong Tai Army. 385 in May, will be Murong Chong Yang captured, Fu Jian big fear, leaving Prince Shou Chang, with hundreds of rides and some of his family fled five to Hill. Fu Jian's death in October 385, West YAN Jun 5 million people in the new level (now Shaanxi Binxian) South was defeated Later Qin, coach high cover down Qin, Yang will take the opportunity to escape Longyou, collect the old unit and restore Chou Chi.
Yang will not children, their cousins YANG Sheng-Chou Chi Kung claims, posthumous title as King Wu Yang.