The rainfall increased the amount of water flowing down from mountains in the north and formed tributaries that merged into the Indus River. That enabled nomadic herding people to settle into villages west of the river. They created order for themselves, growing barley and wheat. They lived in small houses built with adobe bricks. More rainfall meant more food, and they also grew in population. They began domesticating animals as well. As the climate changed again, bringing more rainfall, and on the plains along the Indus River grew jungles inhabited by wild animals. By 2600, they had covered sewers and, drainage systems beneath their streets.