You might want to also ask the folks at r/AcademicBiblical

This question has been asked a few times before, these are probably the best answers: u/tiako https://www.reddit.com/r/AskHistorians/comments/7dztj8/catholic_tradition_holds_that_st_thomas_emigrated/dq1pinc/

u/artfulorpheus https://www.reddit.com/r/AskHistorians/comments/7p634h/how_true_is_the_account_of_st_thomas_having_come/dsi9dmt/

u/talondearg https://www.reddit.com/r/AskHistorians/comments/3b3y89/is_there_any_evidence_of_contact_between_early/csiwe2g/