At the top of the social class system was the Sapa Inca. The Sapa Inca was believed to be a descendant of the sun god, Inti. The Sapa Inca controlled everything in the empire. He could have many wives and hundreds of children from them but he always had one wife called the Coya who was his full sister. This arrangement was to preserve the royal blood. Next were the nobles who helped the emperor with everything. The nobles had special privileges such as not having to pay taxes and the men could have more than just one wife. They helped collect taxes, made sure laws were obeyed, and were army generals and captains. Last were the commoners. This group included farmers and herders. The commoners belonged to groups called ayllus. These were almost just like extended families. Each person had to marry a person in their own ayllu. Each ayllu would have a certain amount of land on which to live and farm. The farmers would have to give two-thirds of their crops to the government who would distribute it and store some for times of disasters such as drought. The farmers would keep the remaining amount for themselves and family.