Peter, Great question! In my case, my progenitor or Gen 1, Patrick McGuire came from Enniskillen , Co Fermanaugh, Ireland sometime around 1810 (I think)...I am Gen 6 and between us the paper trail and headstone path is solid.
Prior to Patrick, I'm not real certain of names but I am certain of Y DNA. We carry a SNP called L69.5+, a son of L513+ and grandson of L21+. That genetic path leads back to the first King of Fermanaugh, Donn Carrach Maguire (Mag Uidhir) reigned from 1264 to d-1302. The Trinity College of Dublin began a Y DNA study in early 2001 that essentially established the Maguire Modal based upon the family testers residing in Co Fermanaugh and Northern Ireland at the time. Further expansion of testing resolution and fidelity as well as surname descendents and sept branching have refined the modal to the Y111 level.
That's roughly 24 generations....however, that whole paper trail thing is spotty!