Your comment underlines the possible merit of adding a field for coordinate references. Just to expand on my earlier post:
A coordinate points to a physical location on the earth, and changes very small amounts over extremely long periods (technically projections, datums and reference systems have, and do, change frequently but can also be converted mathematically); using a proximity search based on coordinates to match places would be computationally easier to manage than matching place names as they change over history.
I imagine it would be easy enough for a programmer to use some mapping API (Google, Microsoft, MapQuest, etc.) to create a point and click interface that returns coordinates to store. Some GIS and programming wizard could even probably create a widget that animates the migration of a family line over multiple generations, or clusters of families that migrate together. Or search people based on proximity to an historic event. Who lived in Boston during the tea party?
Taking it one step further, it would also be possible to 'reverse lookup' a proper 'period' name based on the date of an event. I point and click on Toronto, Ontario, Canada - because I specified that the person is born in 1812, it could recommend that I instead use York, Upper Canada.
Obviously the place names field would still be required.