Spreadsheets are really graphs. This one has time on one axis and space on the other. The space geography is arbitrary but intended to sequence human dispersion from Africa.
I have lots of Teaching Company timelines and felt a yearning to tie them together. For instance, before this exercise I had no idea that while Charlemagne was being crowned Holy Roman Emperor; al-Khwarizmi was doing his algorithms in Persia, the Khmer were taking hold in Thailand, the stone heads were being erected on Easter Island, and the Anasazi were colonizing the Grand Canyon!
Certainly lots more can be done. Hot links would be good.