Totaly
disagree with your answer!
There were "Vlach" population, communities, and political formation long before 13th century in Transylvania (which wasn't a waste just waiting for Hungarians to migrate in)

. There was a continuous movement of people (yes, a migration) both
to and
from Transylvania. Both Romanian Principalities of Moldavia and Muntenia (Wallachia/Țara Românească/Zemli Ungrovlahiskoi) were created in their "consecrated" form by nobles coming from Transylvania and under (and sometimes against) Hungarian patronage at the end of 13th century...
So yes, the Romanian Orthodox lived both before and after the Ottoman conquest (which might favorized them slightly by depopulating some regions in the western planes where they were invited by the Hungarian nobles [and later the Habsburg governement] to colonize the land in search of manpower [alongside with other nationalities too: Germans, Checz, Slovacs, Croatians, Serbs, Ruthenians, etc.] - similarly on how the Wallachian plane of Baragan was populated by the Romanians themselves).
Yet, I do not want to debate too much this aspect as I know you are very entrenched in the Hungarian historiography which... you know what I want to say about...
Cheers!