You might take a look at The Barddas of Iolo Morganwg edited by J. Williams ab Ithel -- you can download it free of charge here:

https://www.globalgreyebooks.com/j-williams-books.html

The writings in it are by Iolo Morganwg, who died in 1826; it contains not only a detailed discussion of reincarnation but also a theory of evolution. The idea of reincarnation was never quite stifled in the West, not least because Greek philosophical writings that affirm reincarnation remained in circulation straight through the Middle Ages.