Every human civilizations which existed had its own specialities and significance . While the Zumarian civilisation is being considered as the oldest of the discovered civilizations, Harappan civilisation has a vast importance in studying about human social evolution. Harappan civilization is otherwise known as Indus valley civilization . The remains of this civilization was found near the banks of river Indus. The first site discovered at the Indus valley civilization was Harappa. This is why Indus valley civilization is otherwise known as Harappan civilization . The main highlight of this civilization was the presence of highly accurate instruments which were used to measure distance , weight etc. The devolepment of sewage system was another peculiarity of this civilization. It paves light to the bronze age, ie ~ 2500 BC. It is considered that the civilization became extinct due to the invasion of Aryans from the west.