My McGinty ancestors in Scotland came from Mayo/Sligo border area near Ballina, Mayo where that name was quite common. They went by Ginty in Ireland but apparently added the "Mc" when they went to Scotland. The Mayo border moved eastward in the late 1800's so towns that were in Sligo before the border change are now in Mayo--creates some confusion in the research. Try looking for other surnames that were associated as friends, neighbors, in-laws in your oldest family records and try to search those names also as frequently these families moved from Ireland together and remained close, inter-married, etc. Good luck!