Pei is a Chinese surname with origins dating back to antiquity. It is most commonly associated with the character 裴 (péi), which itself may have originated from the name of an ancient city. According to traditional Chinese historical records, the Pei clan traces its lineage to the legendary Emperor Zhuanxu, one of the mythical Five Emperors. During the Zhou dynasty, the state of Pei (in present-day Anhui province) gave rise to the surname, with later branches spreading across China. In Chinese etymology, the character 裴 combines two elements: 非 (fēi, “wrong” or “contrary”) and 衣 (yī, “clothing”), but its use as a surname has no direct semantic connection to these components. Instead, it functions as a hereditary clan name. Pei is less common than many other Chinese surnames, ranking around 100th in the Hundred Family Surnames, though it remains relatively frequent in regions such as Hebei, Shanxi, and Henan. Notable Bearers The Pei surname has been borne by several prominent figures in Chinese history and culture: • Pei Ju (547–627), a Sui and Tang dynasty official who played a key role in imperial administration and diplomacy. • Pei Xiu (224–271), a cartographer of the Jin dynasty known as the “father of Chinese cartography” +1][2]  for his precise topographic maps. • Pei Yanling (born 1954), a Chinese opera performer specializing in female roles in the Peking and Taiwanese genres. • I. M. Pei (1917–2019), the renowned Chinese-American architect responsible for the Louvre Pyramid and the Bank of China Tower. Related Forms In Vietnamese, the surname Pei is adopted as Bùi, reflecting the influence of Chinese migration into Vietnam. This variant is common among Vietnamese communities worldwide. Distribution According to the 2010 United States Census, Pei ranked 21,940th in frequency, with 1,183 bearers, 92.6% of whom identified as Asian or Pacific Islander. The surname, though less widespread globally than some other Chinese surnames like Wang or Li, maintains a consistent presence in Chinese diaspora communities. It appears in both simplified and traditional characters, with occasional alternate spellings such as P'ei (Wade–Giles) or Bui (Vietnamese).