Pure Land Buddhism venerates the Buddha Amitābha (Amida in Japanese) and originated in India, before spreading to China and eventually Japan. In Japan, Pure Land (Jodo Shū) and True Pure Land (Jōdo Shinshū) Buddhism were both founded in the 12th century, the former by the monk Hōnen and the latter by his disciple Shinran, but did not enjoy widespread popularity until the 15th century. Both traditions teach that humanity is in an age of spiritual decline, but that sincere faith in Amida Buddha can ensure that one is reborn into the Pure Land, where one will receive instruction in how to achieve enlightenment. However, Shinran also taught that due to the corrupt nature of humanity, there is nothing one can do to cultivate this faith, but rather it must be bestowed upon one by the grace of Amida Buddha. All that one can do is chant the Nembutsu (“Namu Amida Butsu”, or “Hail Amida Buddha”), an expression of gratitude to Amida Buddha, and hope for salvation. This teaching has occasionally been declared heretical by the orthodox Buddhist establishment in Japan, but today it is hugely popular, with Jōdo Shinshū being one of the most widely practiced branches of Buddhism in modern Japan.

15th century Japan was a largely agricultural society, with urban population centres like Kyoto being the exception rather than the norm. The previous capital Kamakura in northern Honshu was another exception, but cities like Sakai, Osaka, and Edo (modern-day Tokyo) did not fully emerge until the end of this period. Although the feudal class system was not made explicit or strictly enforced until the Edo Bakufu took power at the end of the next century, under the Muromachi Bakufu there was still a clear distinction between the kuge (aristocratic nobles who served the Imperial family), the buke (warrior clans who increasingly controlled the affairs of state), and the large mass of commoners including peasant farmers, artisans and craftsmen, and merchants and traders.

The two main competitors for control of the Muromachi Bakufu during the Ōnin War were the Hosokawa clan, led by Hosokawa Katsumoto, and the Yamana clan, led by Yamana Sōzen. The Hosokawa were descended from the Seiwa Genji line of the Imperial family, and along with the Hatakeyama and Shiba clans, held dominant positions in the Muromachi Bakufu. The Yamana clan, by contrast, were relative political outsiders at the time of the Ōnin War, having lost favour after rebelling against the bakufu in 1391, and only recently regained it for their actions against the Akamatsu rebels in 1441. Both clans survived into the Sengoku era and beyond, although they were never again so powerful. The current head of the Hosokawa family, Hosokawa Morihiro, was Prime Minister of Japan from 1993-1994.