The Taika Reforms were a set of doctrines established by Emperor Kōtoku (孝徳天皇 Kōtoku tennō) in the year 645. They were written shortly after the death of Prince Shōtoku and the defeat of the Soga clan (蘇我氏 Soga no uji), uniting Japan. The reforms also artistically marked the end of the Asuka period and the beginning of the Hakuhō period. Crown Prince Naka no Ōe (the future Emperor Tenji), Nakatomi no Kamatari, and Emperor Kōtoku jointly embarked on the details of the Reforms. Emperor Kōtoku then announced the era of "Taika" (大化), or "Great Reform".
The Reform began with land reform, based on Confucian ideas and philosophies from Tang China, but the true aim of the reforms was to bring about greater centralization and to enhance the power of the imperial court, which was also based on the governmental structure of China. Envoys and students were dispatched to China to learn seemingly everything from the Chinese writing system, literature, religion, and architecture, to even dietary habits at this time. Even today, the impact of the reforms can still be seen in contemporary Japanese cultural life.
After the regency of Shōtoku Taishi ended, the Soga clan, from which Shōtoku's ancestry was derived, took hegemony of the Yamato court. The clan was opposed to Shōtoku's son Yamashiro Ōe and killed him in 643. Under the reign of Empress Kōgyoku the Soga clan head, Soga no Iruka, was virtually an almighty leader of the court.
Those who were against Soga's dictatorship included the emperor's brother Karu, the emperor's son, Prince Naka no Ōe, along with his friend Nakatomi no Kamatari, and his son-in-law Soga no Ishikawamaro (Iruka's cousin). They ended Iruka's regime by a coup d'état in 645 (Isshi Incident). As Kōgyoku renounced her throne, Karu ascended to be Emperor Kōtoku.
The new emperor, together with the Imperial Prince Naka no Ōe, issued a series of reform measures that culminated in the Taika Reform Edicts in 646.