Cosmas Indicopleustes, a 6th Century traveler and author of Christian Topography, believed the world was not only flat, but that it fit inside a ‘box’ with a curved lid. It was surrounded by water routes (the ocean), and contained the tallest mountain peak that went up to heavens.

Having to figure out how ‘night’ and ‘day’ worked, he came up with the explanation that ‘angels’ moved the sun behind and in front of the mountain.

His world was bounded by the coast of East Africa, northern Mediterranean, Central Asia, and present-day Sri Lanka (hence, the box).

It turned out this was because these were the only places he had ever gone through his travels.