note the initial /maG/ stuff, singular of Albanian (as proven by the Gypsy example) and likely more generally of Paleo-Balkan languages (possibly the barrow example)
ultimately likely Paleo-Balkan. the /u/ → Slav. /y/ makes sense, while South Slavic /i/ (← /y/) → other langs /u/ would make no sense, so the ultimate source is not Slavic (Romanian movilă and moghilă are most likely Slavic loans). archeology might help