In the late Heian Period (12th century), Aki Province became well known for the Itsukushima Shrine.

Taira no Kiyomori realized the shrine's importance and donated funds for a new complex of buildings and sutra scrolls.

In 1555, Mōri Motonari won the Battle of Itsukushima against Sue Harutaka and established his power in the western part of Honshū.

Mōri Terumoto, one of the Council of Five Elders Toyotomi Hideyoshi appointed for his son Hideyori, sided with Ishida Mitsunari before the Battle of Sekigahara in 1600, and lost Aki and many of his other domains.

After a short rule by Fukushima Masanori, in 1619, Asano Nagaakira was appointed as the daimyō of Hiroshima Domain with 420,000 koku.