Thomas R. answered 01/29/20
Over 25 years of experience and a sense of humor about math
Fascinating question!
The Dacians left little-to-no records of their musical instruments, so most of what we know is based on a combination of later Roman writings about them as well as a few archaeological finds. One instrument was the carnyx, a "brass" instrument made of beaten bronze with an animal head for a bell (the specifics varied depending on whim).
While they were not specific to the Dacians, many ancients had bone flutes made from bird bones, so the Dacians likely had them too.
The closest thing to a guitar I could find was the "crwth", a lyre of the ancient Celts, but records are very thin on this one. They used animal gut for strings and wood for the resonator, so go sacrifice some sheep!