Mataoanu Andrei's question mainly involves Romanian ethnogenesis -- a
topic that seems to generate some intra-Balkan controversy.
In English, Dacian and Thracian refers to two peoples and to two
languages.
The evidence for the languages is extremely meagre. About all the
historical linguists can say is that they are definitely in the Indo-European
family, and that both have been extinct for some considerable time.
As a people, the Dacians (occupying the modern part of Romania facing
the Black Sea) are rather obscure. The Thracians (occupying modern
Bulgaria), however, are well attested. Their history is one of inter-tribal
warfare, and a consequent inability to attain political unity (this is
pretty much the case for the Greeks too, tho' the Greeks did unite when
absolutely necessary).
Historically, these regions of Bulgaria and Romania have undergone several
reasonably well-attested complete language-replacements.
As for Romanian, I've see a few 'nationalistic' accounts of its origin, but
there are some real obscurities. Did it originate in Transylvania with a
subsequent migration over the Transylvian Alps/Iron Gate, or did it emerge in
Dacia?
Linguistically, Romanian is definately one of the Romance languages -- East
Romance is the term I've seen used in English. The Romanian language is also the
essential ethnic marker of a Romanian. In geographic terms, it's OK to call
Romanians Dacians, but this is a little narrow (what of the Wallachians and
Transylvanians?). 'Genetic' arguments for ethnicity are always the hardest
to prove, and the most prone to abuse. It's like asking if King
Ferdinand was a Romanian or not.
Mark.