That's the thing about transhumance peoples, the Vlachs at the time (the word transliterates as shepherd in many Balkanite "languages", very caste like, suspiciously gypsy) went all over the place, they were settling little pockets everywhere between Istria-Thessaly-Pridnestrovie. My favourite theory is they had a founding element of pure and legitimate wewuzmans (probably refuges from former Dacia, 1/16 Decebalusian bloodline) who lost their Y chromosones to Thracians and degenerated into unga bunga hill people who survived as migratory folk in the shitty uberwald niches before the chaos of the Mongol invasions left them best placed to thrive.
My source for this is it sounds cool so must be true.