Tai languages are a completely different language family to Chinese, written using Indian abugidas and largely prisoner to a confluence of religious affectation, court ritual and the popular language of the peasantry as popular literacy never occurred. By contrast, Chinese has an uninterrupted written history spanning thousands of years with world leading poetry, philosophy and science. In terms of historical and linguistic nuance, comparing the two on the basis of an excluded adverb is like eating a banana and declaring it tree-rice.

(Re: child as can't post reply - Assam was always effectively surrounded by larger empires (Tibet, Myanmar, Bengal/Pala/northern India) and a disease-ridden tropical backwater so I guess its cultural and political fate was always to be dominated by larger outside influences.

Actually IIRC there's some linguistic history in the Taic languages that Ahom influence moved eastward through Myanmar. If you look at the geography (much wider spaces) it makes sense that you'd shift focus to richer climes. Perhaps much as the south Indian seafarers who contributed so critically to Cambodia saw it as a vast and wealthy land with geographic echoes of home.)