AFAIK, Merino is mostly farmed in alpine regions, a lot of it in New Zealand. There's a really interesting BlisterReview podcast[0] on technical fabrics and wool, featuring an interview with one of the buyer/sourcers for a big wool company. He explains the farming/shearing/processing of merino pretty thoroughly.

[0] https://open.spotify.com/episode/3X5VBJaRvo1jjVElTjxnnP?si=B...