the tibetan language is most closely related to burmese.the tibetan script/alphabet is indic in origin.the tibetan language and Chinese languages are very different in grammar.tibetan sentence order being Subject-Object-Verb and Chinese being Subject-Verb-Object.although tibetan and Chinese do share a handful of words in common,just like how Chinese and Korean share some words in common,tibetan should not be classified with Chinese.Korean is also not classified in the Chinese language family.Korean is a language isolate,meaning it does not belong to a language family although some scientists suggest an altaic origin.Korean and other altaic languages have the same sentence order as tibetan i.e SOV.these altaic speaking peoples are mostly nomadic like the tibetans and mongols.
currently tibetan is classified in the "sino-tibetan" language family even though the tibetan and Chinese language have nothing in common besides a few words.the CCP uses this classification to justify its occupation on Tibet.