The Aryans were a nomadic people. They probably came from central Asia and entered the Indus Valley through the passes - through the Hindu Kush Mountains which includes the famous Khyber pass.
They brought with them their herds and way of life. They also brought horses and chariots into the Indus Valley. They did not have a central government, instead being ruled by their warrior class, who were called Rajas.
During the Aryan times there was constant warfare as they fought other tribes, and even themselves. Raiding and fighting was their normal way of life.
While there is very little physical evidence of the Aryans, we have something almost as good. The Aryans had a great oral history that they told in song and story. These songs have come down to us and tell us quite a lot about the Aryans.