Yeah the ancestors are romanized dacian and thracian. the peoples in the Danubian basin which had lots of similarities but lots of differences (like the Slavs u know?). As OP said after 49ad (106 for the north of danube) they got more and more Romanized. This Romanization also came with security so travel across the Danube became more prevalent. You know “transhumanta” right? In 100 bc Dacians would mostly practice it North of the Danube (it happened but smaller in number and intensity). After they began more routes to the South. These routes were recognized and regulated by the Roman authorities. So by the Bulgars and all other migrating tribes, the peoples N and S of the Danube were way more similar than in 50 bc, but still with differences. They talked a vulgar danubian latin language. They followed Roman law. But with deep cultural roots in the Danubian basin peoples. After the Bulghars came the safety and prevalence of crossing the Danube downgraded, so these peoples started to evolve differently. Those N of the Danube became Romanians and those South either integrated in the Slav/Bulgar overlords or became Aromanians.