Throughout history, our ancestors migrated from their homelands and adopted new ones. Not all crossed huge oceans to their new homes. Some of them crossed mountains or rivers or moved their households to a neighboring village. Others did not have to move, but simply found themselves living under new rulers who had conquered them.
National boundaries are a fairly recent innovation in history.
And, in many cases, those national boundaries have been very fluid. Even if we find that our ancestors never migrated, chances are someone from the family did leave. The reasons are legion. They may have sought adventure or new fertile ground for their farms. Men and women married and moved to the village of their spouse's family.