An idea just popped into my head at random concerning a wanked Tibetan Empire. IIRC the Tibetans actually captured Chang'an briefly during one of their wars with Tang at the zenith of their power. Now, let's say Tibet had ended up, by whatever means (perhaps a breakup of Tang from within coinciding?), totally defeating Tang, afterwards establishing permanent control over swathes of western China, from Ordos through Chengdu to Yunnan and including a significant portion of Yellow River plain.
Could these conquests have spurred a Sinicization of the Tibetan Empire in the same mode as the previous Turkic dynasties during Eastern Jin and OTL's Jurchen and Mongols? If so, what would such a state and culture look like, and what would the exchanges look like, and effects on subsequent Tibetan history be?