How did the cartographer know the general outline of western south america? Magellan didn’t get passed the straits of magellan till 1520. Who was there before?...
Always wondered that myself with these old maps. How did they know the relative size of everything?
They could judge distances by how long to took to go from point A to point B, and roughly how fast they were going (north-south was probably easier to discern than east-west).