Chà Ângan () or Ding'an () was a state in Manchuria that existed from 938 to 986. It was the successor state of Parhae (Bohai) founded by Yà Âl Manhwa (Lie Wanhua).
The early history of Chà Ângan is mostly unknown. Large number of rebels emerged in the former territory of Parhae after the kingdom's conquest by the Liao dynasty in 926, although most were quickly defeated by Liao forces. After the Liao puppet state of Dongdan was abolished and the main Liao forces left the region, General Yà Âl Manhwa (Lie Wanhua) established Chà Ângan in the mid-930s to prevent a full occupation by the Liao dynasty. Chà Ângan is recorded to have enlisted the assistance of neighboring tribes with the hopes of overthrowing the Liao dynasty, but apparently failed to do so.
In 970, the king paid tribute to the Song dynasty together with the neighboring Jurchens. On all four occasions in which Chà Ângan envoys were able to reach the Song court, they were attached to a Jurchen mission. Chà Ângan was a poor state and was unable to send their own independent missions. The History of Song claims that the Chà Ângan people's origin can be traced back to the former confederacy of Mahan. However, the Mahan confederacy in the distant south of the Korean peninsula had disappeared for almost a millennium by the 10th century, and Chinese scholars consider this record, written in the Yuan dynasty, to be an error. Meanwhile Korean historians consider the History of the Song to be accurate. Goguryeo (the predecessor to Parhae and Chà Ângan) had traced part of its heritage with the Mahan as its lands were previously part of Goguryeo before it became Parhae territory, and Goguryeo had acquired it from Baekje. In a message to the Song emperor in 981, described his people as the "remaining commoners of Bohai" who lived in the former land of Goguryeo. The purpose of Chà Ângan's tributary mission was a proposal for the Song and Chà Ângan to ally and initiate a joint attack against the Liao, which the Song declined due to the Liao's military prowess. Oh also described his territory as having been heavily damaged by the Liao and was under threat of imminent destruction.
The Khitans did not recognize Chà Ângan as a state and called their people the Ujae tribes. In 975, the Liao dynasty once again invaded Chà Ângan, which failed. In 976, the Yà Âl clan was replaced by the Oh clan, and Chà Ângan was ruled by O Hyà Ânmyà Âng (Wu Xuanming) until before it was finally destroyed by the Liao dynasty in 986 CE. Korean historians theorize that the Oh Clan's replacement of the Yà Âl Clan may have been violent and could have played a role in the destruction of Chà Ângan. According to the history book Goryeosa, tens of thousands of Parhae refugees fled to Goryeo in 979, and was recorded as the largest Parhae migration since the 936 exodus when Parhae Crown Prince Tae Kwanghyà Ân had similarly led tens of thousands of refugees into Goryeo.
Although Chà Ângan officially fell in 986, records indicate that Parhae resistance continued for several years, notably in 994. The Liao responded with punitive campaigns until they established three military outposts in the lower Yalu River and completely occupied the area in 991. The last remnants of Parhae resistance from the former state of Chà Ângan were destroyed by 999.