An : the Tibetan transcription of the Chinese 安 (pinyin: An), a family name given to people of Sogdian origin hailing from Bukhara.
See Takeuchi contracts p. 130-131.
See Encyclopædia Iranica: Personal names, Sogdian i. In Chinese sources (Y. Yoshida), originally Published: August 15, 2006 Last Updated: August 15, 2006. (22/06/2018)