Iraq sits between two of the most famous rivers in the world: the Tigris and the Euphrates. Thousands of years ago, people built some of the first cities between these rivers. The area was called Mesopotamia, which means "land between the rivers." The rivers provided water for farming, drinking, and transportation. On October 3, 1932, Iraq became an independent country and joined the League of Nations. Before that, Britain had controlled the region after World War I. The British had drawn Iraq's borders on a map, grouping together people who spoke different languages and followed different traditions. Iraq's geography created both advantages and challenges. The flat land between the rivers, called the fertile crescent, produced wheat, barley, and dates. But the deserts to the west and south made travel difficult. Mountains in the north provided a natural border with Turkey. Below the ground, Iraq held something even more valuable than river water: oil. The discovery of massive oil reserves changed Iraq's economy forever. Oil became the country's main source of wealth. Iraq's location also made it important to world politics. It shares borders with six countries, and its rivers flow from Turkey through Iraq into the Persian Gulf.