This is awesome! I've been thinking about making something like this, but felt like a huge undertaking. One of the major reasons I wanted it was to visualize how (ie under which treaty) were boundary lines moved or redrawn.
Be careful assuming that the dates are correct and that the borders are drawn exactly where they should be. This map is a great guide, but don't base decisions on it.
Also many historical treaties did not define borders to the level of detail they we are used to today.
Also many historical treaties did not define borders to the level of detail they we are used to today.