Thanks for that link, I love studying old maps, they reveal a lot.
When I was about 12 I visited a friends house in France, his family owned a huge vinyard and they lived in a 700 yr old estate...in the basement, hanging on a damp old wall in the gloom was a map of America dated from the 1600's. Everything west of the missisippi was marked "terre inconnu", "unknown territory".
I must've stood there looking at that map for a solid hour, mesmerized.