Nanzhao, Vietnam and even Tibet are a few candidates. Would define Indianized as being from the Indian subcontinent or at most culturally linked regions like much of SE Asia and areas with significant Indian cultural influence such as Tibet and Yunnan.
What if the Tai / Shan or other northern peoples around Burma for example managed form a Mongol-like horde and occupy significant parts of southern China (at minimum) from the south during large periods of strife? Apparently even in their divided state, they still managed to wreak havoc along the Irrawaddy / Mekong rivers and were a constant threat in Yunnan and on the western borders of the Laotian kingdoms in OTL.
There is another interesting ATL idea via a no/screwed-Islam scenario that leads to much of Central Asia (beyond Afghanistan) being more culturally linked with India (as well as China to some degree) compared to OTL and significantly influencing the Turkic and other Central Asian peoples, who later end up conquering China.