Answer: The ancient Greeks did not have fertile land to grow crops.
Step-by-step explanation:
Most early civilizations like the Mesopotamians and the Egyptians were able to form because they had access to rich and fertile land for agriculture to support their population. The Greeks did not have these because their lands were mostly on mountainous regions that did not have a lot of fertile land.
In order to get over this, the Greeks established strong armies and navies that enabled them to conquer other areas which had better land than they did. They would then take resources from those lands to feed the homeland.