Chronas is a new site that lets you used a time “slider” at the bottom to see how the world looked at pretty much any given date during the past 2000 years. If you click on the countries/regions/empires shown, then it will show you the appropriate Wikipedia entry.
It’s still working out its kinks — it wouldn’t let me view it on a mobile device and, even though it says you can view it on browsers other than Chrome – I wouldn’t.
I’m adding it to The Best Websites For Teaching & Learning About World History, though I’m not quite ready to add it to The “All-Time” Best Social Studies Sites.
Thanks to Google Maps Mania for the tip.
Here’s a video describing how it works: