The Indus valley was overrun by the Aryans in 500 B.C.E. with some groups of the Aryans reaching the southern cone of the Indian subcontinent (shown above). The Aryans were known as aggressive people that often fought for land. Therefore, when they expanded into the Indus Valley Civilization, they came into contact with the Dravidians. Before the expansion, Aryan political stature involved one tribal chief (known as a raja) that governed with a council of village elders. There were many chiefdoms that resulted in the conflict between Aryan tribes. This political structure changed in some areas however, and councils of elders acted as the central political authority. In most places, it remained with one tribal chief. The chiefdoms became regional kingdoms with more permanent capitals. There were no imperial states until the fourth century. This picture of a map of the Indo-Aryan Migration into India was chosen to show the movement of Indo-Aryans since it affected their government greatly, and caused it to change from chiefdoms to regional kingdoms.