But they were successful enough that their neighbors, Spain, became interested in their own route to the Indies. And that brings us to Columbus. But first, let's dispel some myths. One, Columbus and his crew knew the Earth was round. He was just wrong about the Earth's size. Columbus used Ptolemy's Geography and the Imago Mundi based on Muslim scholarship and ended up overestimating the size of Asia and underestimating the size of the oceans. Two, Columbus never thought he'd made it to China.