Cui (), alternatively spelled Tsui or Tsway, is one of the 80 most common surnames in China, with around 0.28% of the Chinese population having the surname (around 3.4 million in 2002). It is also one of the most common surnames in Korea, with around 4.7% of the population having the surname in South Korea (2.4 million in 2013). In China, Cui is commonly found in Shandong and Henan, as well as provinces in the northeast and other areas of China, such as Heilongjiang, Liaoning, Hebei, Jiangsu, Shanxi, and Jilin. It is romanized as Chui in Hong Kong and Macao (Cantonese), Choi in Macao (Cantonese) and Malaysia, Choi in Korean, Thôi in Vietnamese and Tsoi in Cyrillic. Origin One origin of the surname came from descendants of someone who originally held the Jiang (姜) surname in the state of Qi, founded by Jiang Ziya (姜子牙). A grandson of Jiang Ziya named Jizi (季子), an heir apparent, chose to relinquish his claim to the throne in favour of his brother Shuyi (叔乙), and went to live in the Cui estate (崔邑, in present-day Shandong). His descendants later adopted Cui as their surname. During the Tang dynasty the Li family of Zhaojun 赵郡李氏, the Cui family of Boling 博陵崔氏, the Cui family of Qinghe 清河崔氏, the Lu family of Fanyang 范陽盧氏, the Zheng family of Xingyang 荥阳郑氏, the Wang family of Taiyuan 太原王氏, and the Li family of Longxi 隴西李氏 were the seven noble families between whom marriage was banned by law. Moriya Mitsuo wrote a history of the Later Han-Tang period of the Taiyuan Wang. Among the strongest families was the Taiyuan Wang. The prohibition on marriage between the clans issued in 659 by the Gaozong Emperor was flouted by the seven families since a woman of the Boling Cui married a member of the Taiyuan Wang, giving birth to the poet Wang Wei. He was the son of Wang Chulian who in turn was the son of Wang Zhou. The marriages between the families were performed clandestinely after the prohibition was implemented on the seven families by Gaozong. Their status as "Seven Great surnames" became known during Gaozong's rule. The surname is one of the five surnames, now the most common surnames in Korea, closely associated with the six villages that formed the earliest state of Silla. Many non-Han Chinese groups adopted the surname Cui. During the Qing dynasty, the