The Karakachans / Sarakatsani are Vlachs, Hellenistic Thracians or Greek people?
In the Ottoman Empire, the Karakachans were a relatively independent ethnic group and experienced the trade of meat (lamb and mutton) and wool. They usually spent the summer months in the Rhodope Mountains, in present-day Bulgaria, and returned south to present-day Greece for the winter. The migration began on St. George's Day and the return migration on Dimitrovden.
https://www.youtube.com/watch?v=CkDj8j758JU&t=81s