Nevertheless, the kingdom survived for roughly a century, benefiting from sea trade, and from the advantageous location of Ōzato Castle, situated atop tall bluffs, with an inlet from the sea and its own dedicated dock.
On 24 May 1904, during a heavy thunderstorm, the Japanese Fourth Division attacked the walled town of Chinchou (modern-day Jinzhou District 金州), just north of Nanzan hill.
The Lord of Ozato fled south and, along with his followers, formed the kingdom of Nanzan (南山, Southern Mountain), while the Lord of Nakijin, based some distance to the north, declared himself king of Hokuzan (北山, Northern Mountain).
Chūzan entered a tributary relationship with Ming Dynasty China in 1372, and Hokuzan and Nanzan were granted similar commercial status shortly afterwards.
Unno, Taitetsu and James W. Heisig (editors), The Religious Philosophy of Tanabe Hajime: The Metanoetic Imperative (Nanzan Studies in Religion and Culture), Asian Humanities Press (June 1990), ISBN 0-89581-873-6, ISBN 978-0-89581-873-7.