While Europeans were making important advances in the technological knowledge necessary to complete a voyage across a vast and unfamiliar ocean, their ships and instruments had not developed without contributions from nonEuropeans. For example, sailors relied on such instruments as the compass and the astrolabe, but their ships themselves benefited greatly from a change from clumsy square sails to the triangular sail. This improvement, borrowed from Arab seamen, facilitated the building and use of smaller and more maneuverable ships that could more safely navigate through a difficult ocean.

In addition to this type of knowledge crucial for passage to the New World, once there the explorers and conquerors relied heavily on native peoples for their knowledge of geography, their ability to survive in environments that Europeans could barely tolerate, and their willingness to ally with the invaders to defeat other native enemies...