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.
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