Tokuyama Domain

Mōri Narikata, a son of Mōri Terumoto and brother of Mōri Hidenari was granted estates with a kokudaka of 31,000 koku and was authorized to establish a cadet branch of the Mōri clan. As his seat was initially located in Kudamatsu, Suō Province, the domain was initially referred to as "Kudamatsu Domain". In a land survey of 1625, it was estimated that his actual kokudaka was more than 40,000 koku. The domain received official recognition by the Tokugawa shogunate only in 1634. Mōri Narikata spent most of his time in Edo, visiting his estates only in 1634. For the most part, his holdings were administered by officials from the parent domain dispatched from Hagi; however, many of the domain's samurai were originally ronin made masterless by the Battle of Sekigahara, or else third sons of retainers of the parent domain who had poor prospects for employment closer to home.

In June 1650, Mōri Narikata moved his seat to a place called Nogami, which he renamed "Tokuyama". The new location was more convenient for trade and commerce, and the domain was renamed "Tokuyama Domain". In 1716, under the third daimyō, Mōri Mototsugu, there was a heated dispute between Tokuyama Domain and the parent domain over the felling of trees (the Manyakuyama incident), which resulted in intervention of the shogunate and attainder of Tokuyama Domain for "disrespect". However, through the efforts of Mototsugu's son Mōri Mototaka and senior retainers, the domain was revived in 1719, albeit with a reduction in kokudaka to 30,000 koku. In 1836, the eighth daimyō, Mōri Hiroshige, was raised in status to "castle-holding daimyō", and Tokuyama jin'ya was renamed "Tokuyama Castle" and the domain's kokudaka reverted to 40,000 koku. His successor, Mōri Motomitsu, ruled to the Meiji restoration. At the time of the abolition of the han system in 1871, it was estimated that the domain's actual kokudaka was more than 69,000 koku.

On July 26th, 1945, Tokuyama Castle was destroyed by the Tokuyama Air Raid.