A historical map can make conquest look like a change of color.

A map redrawn shows a territory changing colour. What happened on the ground was people losing homes, languages, laws, and often lives, compressed into a legend and a shade. Cartography necessarily abstracts, and the abstraction is very clean, which is why looking at historical maps can leave you with an oddly bloodless sense of how the shapes came to be.

When a map shows a change, ask what the change consisted of for the people already there. Look for a first-hand account of the same shift. The map is an accurate summary and it is not the event.