Answer:
The main purpose of this map is to show the trade route across Egypt.
Step-by-step explanation:
The details provided in the question suggests that the map is a trade route map. A trade route map is used to indicate the trade pathways and places of stoppings. Such maps were used mainly for commercial purposes for transporting cargos and trades from one place to another.
In the given trade route map, the trade route across Egyptian empire is revealed. The map shades particularly Egyptian empire and it's trade route that's spread across the empire and connects with other regions.
Therefore, the main purpose of this map is to reveal trade route across Egypt.