After Toyotomi Hideyoshi's conquest of Kyushu in 1587, Kuroda Kambe was awarded a 123,000 koku (according to one theory, 160,000 koku) domain in northern Kyushu, with Nakatsu as one of his strongholds. In 1600, his son Kuroda Nagamasa, who had distinguished himself in the Battle of Sekigahara, was transferred to Fukuoka Domain for an additional 523,100 koku. At the same time, Hosokawa Tadaoki, who also sided with the eastern army at the Battle of Sekigahara, received 399,000 koku was transferred from Miyazu Domain in Tango Province, and established Nakatsu Domain under the Tokugawa shogunate. In 1602, Tadaoki moved his seat to Kokura Castle, retaining Nakatsu Castle as a branch castle. In 1632, the second daimyō of the domain, Hosokawa Tadatoshi, was transferred to Kumamoto Domain.
He was replaced by Ogasawara Tadamasa from Akashi Domain as daimyō of Kokura Domain and assigned Nakatsu Castle to his nephew Ogasawara Nagatsuji as the head of a cadet branch of the clan, and received official recognition as an independent daimyō. In 1698, the third daimyō of Nakatsu, Ogasawara Nagatane, was accused of mismanagement and misbehavior in daily life. However, instead of attainder, the Tokugawa shogunate ordered that the parent clan in Kokura replace him with his younger brother Ogasawara Naganobu with his kokudaka halved to 40,000 koku, which was halved. In 1716. The fifth daimyō, Ogasawara Nagao, passed away at the age of seven, and his younger brother, Ogasawara Nagaoki was transferred to the Anji Domain (10,000 koku) in Harima Province.
Nakatsu was then awarded in 1717 to Okudaira Masanari, formerly of Miyazu Domain, with a kokudaka set at 100,000 koku. The Okudaira clan would continue to rule Nakatsu for nine generations and 155 years until the abolition of feudal domains and establishment of prefectures in 1871. The eighth daimyō , Okudaira Masamoto strongly advocated restoration of the national isolation policy after the arrival of the Perry Expedition and expelled the foreigners, contradicting the idea of opening up the country of his retired grandfather Masataka, who held the real power in the domain's administration. When Masataka died in 1855, he began reforming the domain's military, including building artillery forts. As the Okudaira clan was a prestigious fudai daimyō clan, when the pro-Tokugawa forces were defeated at the Battle of Toba-Fushimi at the start of the Boshin War, he defected to the imperial side and dispatched forces in the Aizu War against pro-Tokugawa remnants.
Following the Meiji restoration, Nakatsu was incorporated into Oita Prefecture via Nakatsu Prefecture, Kokura Prefecture, and Fukuoka Prefecture.
As with most domains in the han system, Nakatsu Domain consisted of several discontinuous territories calculated to provide the assigned kokudaka, based on periodic cadastral surveys and projected agricultural yields.[4][5]
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