As a child of the Cold War where it seems like political boundaries were more or less immutable this video of the last 1000 years of Europe is a nice reminder of just how much these boundaries change.
Note the Mongol invasion on the right hand side of your screen.
http://www.youtube.com/watch?v=qSScIvenIzo
Thanks to my brother Neil for pointing this out to me from a website called LiveLeaks.
eaves.ca 
Very cool…be nicer with a visible time-line / progress bar…
Its time we overcame our tribal past…see my blog post “America…we have a problem.” at http://thedigitaldruid.org