I've recently developed an interest in the Sassanids, and I was wondering if we knew what happened to them after the Islamic conquests.

I know that some of the cadet branches such as the Bavanids would continue to wield power in Central Asia for some time after, but I'm curious if any information survives about the main line- as far as I can tell, the last known record of the dynasty mentions that they fled to Tang China, and that Khosrau (Khosrow?) VI was seen fighting with the Sogdians near Bukhara.

Is there any more surviving information about what happened to the Sassanids? Might there be surviving descendants of them living in China today?