One of the more curious details about the history of astronomy in China is the fact of foreign leadership of the/an imperial astronomical bureau by Indian, Persian, and Muslim clans from the eighth century on and, contrarily, of the negligible influence that that leadership had on the Chinese tradition of tianwen 天文 and li 曆. From the time of their entry, in the Yuan 元 (1271–1368), Muslim astronomers were segregated into their own bureau, but such, to our knowledge, was not the case for the astronomers of the Nestorian Li 李 and Buddhist Gautama 瞿曇 clans in the Tang 唐 (618–917), making it difficult to understand how little their directorships shaped the Chinese tradition. To shed new light on the apparent anomaly posed by the foreign/expatriate leadership of the Tang bureau, this paper will attempt to place it into the context of broader institutional ambiguities and evolutions over the centuries leading up to the Tang: the integration of ‘internal foreigners’ in the politics and practice of the astral sciences since the Han 漢 (206 BCE–220 CE), precedence for multiple directors and multiple directorates prior to the Yuan, and the gradual isolation of the astronomical bureau(x) through bans and bureaucratic restructuring from the sixth century on.