For 10 points - name this civilization, whose two major cities were Mohenjo-daro and Harappa, and which is named for the river valley system in which it is located.
The recently discovered Ravi phase pushes its history back to 3300 BCE, long before the previously known Kot Diji Phase.  Using four-to-five-character-long inscriptions on seals, this people's language has been tentatively identified as Dravidian.  Akkadian references to "Meluhha" and "Makkan" give evidence of their foreign trade.  Probably reaching from Sutkagen Dor near the Arabian Sea to Rupar in the Simla Hills, its main cities were located in present-day Pakistan.  For 10 points - name this civilization, whose two major cities were Mohenjo-daro and Harappa, and which is named for the river valley system in which it is located.
The recently discovered Ravi phase pushes its history back to 3300 BCE, long before the previously known Kot Diji Phase.  
Indus Valley Civilization (prompt on Harappa or Mohenjo-Daro)