I've been doing a lot of reading lately on lost cities, phantom islands, and the like, and I've come across some "historical" maps that time has proven to be more like alternate history. Maybe you'll find some inspirations from these examples of terra fabula, too:
an island. It ddin't finally settle on the North American mainland for good until the 1770s.
1474 map which gets the the earth's circumference wrong and has Cathay and Cipangu (Japan) just a quick sail away. Hey, this map was good enough for Columbus! Helpfully, the real North America appears ghostly in the background of this reproduction.
Taprobana, which may have become Ceylon, or Sumatra--or disappeared all together. It was an important trading port between east and west. Marco Polo thought Adam was buried there, on the top of Mount Serendib.
4 minutes ago