What was one primary form of currency used to pay workers and collected as a tax in Sumer?

The oldest examples of Ancient Mesopotamia writings are documents concerned with goods and trade and include records of taxes, tithes, and tributes. ... The primary focus of early property taxation was land and its production value and the taxes were often paid with a portion of the crop yield, or some other food

answer; i believe the correct answer is prefrontal cortex;