Mōri Motonari was a prominent daimyō in the western Chūgoku region of Japan during the Sengoku period of the 16th century. The Mōri clan claimed descent from Ōe no Hiromoto (大江広元), an adviser to Minamoto no Yoritomo. Motonari was called the "Beggar Prince". He was known as a great strategist who began as a small local warlord (jizamurai) of Aki Province and extended his clan's power to nearly all of the Chūgoku region through war, marriage, adoption and assassination.

The Sengoku period, also known as Sengoku Jidai is the period in Japanese history in which civil wars and social upheavals took place almost continuously in the 15th and 16th centuries. Although the Kyōtoku incident (1454), Ōnin War (1467) or Meiō incident (1493) are generally chosen as the Sengoku period's start date, there are many competing historiographies for its end date, ranging from 1568, the date of Oda Nobunaga's march on Kyoto, to the suppression of the Shimabara Rebellion in 1638, deep into what is traditionally considered the Edo period. Regardless of the dates chosen, the Sengoku period overlaps substantially with the Muromachi period (1336–1573).