It seems that words for tea that derived from "cha" spread across land, while the ones originating from "tea" developed over sea routes.
https://qz.com/1176962/map-how-the-word-tea-spread-over-land...
https://qz.com/1176962/map-how-the-word-tea-spread-over-land...
It is true that the British brought large scale tea production to India, but the plant is endemic to India and its local consumption long predates the British (though the exact origins are somewhat obscure).
https://en.m.wikipedia.org/wiki/Indian_tea_culture