Where did the founders of the Harappan Civilization originate?

The Indus River civilization, commonly called the Harappan Civilization was an advanced civilization that grew along the Indus River Valley in present-day Pakistan.  It encompassed a larger area than both Egypt and Mesopotamia and supported a very large population.  Two major cities, Harappa, and Mahenjo-daro anchored a sophisticated culture that was known for its urban planning techniques.  Harappan Civilization is known for its sophisticated water systems and use of standard-sized mud bricks in all of its structures.  The golden age of Harappan Civilization occurred between 2500-1900 BC.  The original inhabitants of Harappan Civilization were people from the west of the Indus River. These people are known as the Mehrgarh culture and many elements of Harappan culture originated in the small farming villages of these people.  The Mehrgarh slowly migrated toward the Indus River system to support larger populations.