Tang Taizong

Li Shimin helped his father found the Tang dynasty, then took the throne as Emperor Taizong after killing his brothers in the Xuanwu Gate incident and forcing his father to abdicate. Despite that violent start, his Zhenguan era became a byword for capable rule: he listened to frank advisers, kept taxes light, reformed the law code, and expanded the civil service examinations. He extended Tang power deep into Central Asia and took the title of Heavenly Khan from the steppe peoples. Later Confucian writers treated his reign as a standard against which other emperors were measured.