There must be a reason they don't teach this in school
I think most even vaguely educated people have a sense that boundaries change a little over time.
But who knew the changes were so extreme - or that so many now-major countries, like Germany and Italy for example, weren't even countries until relatively recently?
Why isn't this taught in school?
Is it possible that the new central governments which control education don't want people to contemplate the world order?
For example, I'm sure when England occupied all of Ireland no time was devoted in history class to the days when Ireland was independent and made up of numerous smaller political units.
I'd like to see a similar dynamic map of North America, one that shows the 500+ Indian nations not-so-slowly engulfed by one unit and Palestine and how it's been eaten away over the last sixty years by the rapacious cancer that is The State of Israel.
Could this be improved on? Yes, with a simple time scale, but this a great start.
Facts are the most subversive things there are which is why so much is done to suppress them.