Beer making is a very ancient art and the oldest known records are credited to the Sumerians, about 7,000 years ago. They perfected this art and passed it on to the Babylonians, who know how to make at least 20 different types of beer. It was exported as an important commodity throughout the civilized world at this time. In ancient Babylon, certain amounts were rationed out to the public in relation to their class. The average worker was given a ration of 2 liters per day, and the higher members of society like priests were allowed as much as 5 liters. Beer was bartered rather than sold at this time.