One thing to recognize, is that borders have traditionally been much fuzzier than they are now. In days of the Polish-Lithuanian empire, for instance, you'd have towns that considered themselves German, with ties to the old Holy Roman Empire. And these towns, even though they might be surrounded by the lands of Polish lords, wouldn't necessarily maintain fealty to the Polish king. In a lot of ways, you could even have two or three different, overlapping "territorial" claims within the same geographic space, without having an inherent conflict.
1250 is very interesting. Think of all the modern day cultures that the Mongol Empire encompassed at the time. Just visually impressive to watch it grow in the years leading up to the peak.
Also, anyone else get an urge to play Civilization after playing with this map for a while?
It was a lot of fun to run the clock back to the point where neolithic cultures predominated and see how much the colored areas shrinked. A long period of time in human history. A blink of an eye in geological time.
Short of showing blurry borders and a shorter time granule than years, this is what you're going to get. For this specific example, 410 is the commonly cited year, although everyone recognizes that it was not such an abrupt process. See http://en.wikipedia.org/wiki/End_of_Roman_rule_in_Britain.
The UX on this is very confusing. I'd love to see some great things, like the start of renaissance, but I have no idea how to make the site start the animation. If that's what it does, animate?
I noticed it doesn't work at all for me in Firefox 29, but works fine in the latest Chromium build. Those are the only two browsers I use. Try Chrome/Chromium or another non-Firefox browser.
