My guess is Marmatian Rutheneans? In the Romanian region of Maramureş with a sizable Ruthenean, or
Russyn, minority.
Rutheneans are interesting. The majority of them appear to make up a huge part of nowadays'
Ukrainians, though a lot also prefer to consider themselves
Russian instead. From what I understand — as their name more or less suggests — they're actually core descendants of
Kievan Ruś.