Historians often need to "read" nonwritten materials such as old maps. Historical maps include many of the things that modern maps do: bodies of water, country borders, locations of mountains, cities and towns. Historical maps can also tell us much about the people who drew them and what they both knew and did not know about a given geographical area. Many old maps are inaccurate compared to modern ones, but this does not make them useless to the historian.

Often the most important pieces of information that we can learn from historical maps are about the mapmakers themselves. Like other primary sources, old maps illuminate the mapmaker's understanding of the world. With this information, the map reader can often infer what people thought about these territories at the time the map was drawn.

For example: A world map drawn in 1500 by a Muslim mapmaker will look much different from one drawn by a Christian mapmaker. These maps will most likely emphasize different geographical areas and might place the central region of their own religion at the center of the map. Even if no textual records existed, the reader can learn a great deal about Christian and Muslim culture in 1500 by comparing the two maps.