In “Interpreters in Early Imperial China” (2011), author R. Lung wrote:

“The Sogdian language, of ancient Iranian origin, was widely recognized as the commercial lingua franca on the Silk Road, from Central Asia to Chang’an of imperial China in the first millennium…. Some of its alphabets were even borrowed in the creation of the Turkic language in the eight century…. Sogdians typically grew up speaking at least the Sogdian, Turkic, and Chinese languages”… hence, many Sogdians played the role of interpreters along the Silk Road…

According to Chen’s 2012 book on medieval multicultural China published, Sogdians were not just merchants and interpreters but “entertainers, horse breeders, craftsmen, and transmitters of ideas”… their influx was “a major factor in the cultural history of China”…

[pic Silk Road Religion: …for educational purposes only]