Bar Sauma was born c. 1220 in or near modern-day Beijing, known then as Zhongdu or Khanbaligh. According to Gregory Barhebraeus he was of Turkish Uyghur origin. Chinese accounts describe his heritage as Wanggu (Ongud), a tribe of Turkic origin classified as part of the Mongol Caste of the Yuan Dynasty. The name bar Ṣauma is Aramaic for "Son of Fasting" though he was born to a wealthy family. He was a follower of the Nestorian faith (see: Nestorianism in China), and became an ascetic monk around the age of 20 and then a religious teacher for decades.