Zhang Yang Castle, also known as Zhanggian Palace, is a royal palace located in northern Zhang Yang, Okatabawashi. First constructed in 1394 and reconstructed in 1767, it was the main and largest palace of the Five Grand Palaces built by the Okata Dynasty. The name of the palace, Zhang Yang is named after the first emperor of the Yeu Dynasty, Yeu Zhang
Emperor Yeu, During his reign Okatabawashi became was at the height of it's power and Yeu Wang was known as the "dragon conquerer"
Nearly destroyed by the Japanese government in the early 20th century, the walled palace complex is slowly being restored to its original form prior to destruction.