Hungary, and its kings had influence, in Transylvania. According to Saxon histories, King Geza of Hungary invited the Saxons to populate and protect the land of Transylvania...
The problem is that it was populated. There were Romanians and Roma who lived there. The difference was that they had a different religion. The Saxons at the time were Catholics. This was more likely the reason for the invitation.
The is plenty of history between Transylvania and Hungary but also with Romania.