The people of Mesopotamia were protected by the

The people of Mesopotamia were protected by the "Zaragos and Taurus Mountains".

Explanation:

The mountains are the site of many temples of primitive storm-gods. The ancient Syrians believed torrential thunderstorms in these mountains to be the work of the storm-god Adad in rising and flooding the Tigris and Euphrates rivers and thus fertilizing their property.

To the north of Mesopotamia the Taurus Hills situated, extended to the Mediterranean Sea and then westward from northern Iraq. Both the Tigris and Euphrates rivers rise at the eastern end of these mountains, where they meet northern Turkey's Pontus Mountains and Iran's Zagros Mountains.