Pre-BOBW, I would guess that the Borg 'scooped' up civilizations en masse, cannibalized the technology, and then disposed of the people much like we'd throw away a candy wrapper.
Guinan tells that the Borg invaded her world and scattered her people across the galaxy. I would take that to mean that their world was destroyed, and everyone who escaped went their separate ways.
Guinan tells that the Borg invaded her world and scattered her people across the galaxy. I would take that to mean that their world was destroyed, and everyone who escaped went their separate ways.