Histories

Phanes had left sons in Egypt [30,27] (nation), Africa Egypt; these they brought to the camp, into their father's sight, and set a great bowl between the two armies; then they brought the sons one by one and cut their throats over the bowl.

When all the sons had been slaughtered, they poured wine and water into the bowl, and the mercenaries drank this and then gave battle. The fighting was fierce, and many of both armies fell; but at last the Egyptians were routed.

I saw a strange thing on the site of the battle, of which the people of the country had told me. The bones of those killed on either side in this fight lying scattered separately (for the Persian bones lay in one place and the Egyptian in another, where the armies had first separately stood), the skulls of the Persians are so brittle that if you throw no more than a pebble it will pierce them, but the Egyptian skulls are so strong that a blow of a stone will hardly crack them.

And this, the people said (which for my own part I readily believed), is the explanation of it: the Egyptians shave their heads from childhood, and the bone thickens by exposure to the sun.