I love the website, such a great find tbh!! But some things seem missing depending on the use.  
  
If you're giving the option for different historical periods, since those can often be approximations, it seems necessary to add a list of all available territories in different periods at once, and allow user to pick from the list. I mean, in modern times that'd be cool as well. But historical borders get trickier the older.  
  
For my use, something like so would at least let me know the Erlitou culture is not listed but the Xia dynasty is (which today are treated closely, they could be listed as one for this purpose)  
  
Also the very long lasting Yangshao/Longshan cultures before the Xia Dynasty aren't listed, even though The height of the Yangshao culture had relatively advanced "urban" development. Their larger settlements had over 400 thousand square meters, with the more common settlements being around 200 thousand square meters. In the picture there are other middle neolithic cultures in the region, many doing stuff like sculpture and jewlery already, so It'd be cool to see those included. I'm sure there's lot to add in this sense for other parts of the world, too.

I will take this opportunity to suggest a longer timeframe too, in the sense that it would be fun to compare, like, the size of Pangea or something like that. We could make the map change and put Brasil over Pangea. lol.

On a note, I'm a UI/UX designer, please send me a message if you'd like more details on improvement suggestions :)

I'm learning about the Paleo and Neolithic periods in the region and I noticed there's quite a few cultures with alternative names, and some that aren't included. The Xia Dynasty should also be found if people search for Erlitou Culture. More in the post.