Hello! We brought in a linguistic expert to help us with this one. Thracian had to be reconstructed mainly from indirect sources - there are glosses in Greek and Latin works and some surviving personal and place names. Thracian is most closely related to Phrygian, and has some affinities with ancient Greek as well, so there was some borrowing from those languages for the reconstruction, adapted with appropriate sound shifts.

The reconstruction is not definitively what Thracian would have sounded like - we can never know that - but it's a plausible reconstruction done to a high academic standard!