From InfiniteLoom
Harappan Civilization
http://www.harappa.com/indus/39.html
3000 - 1500 BCE
http://en.wikipedia.org/wiki/Harappa
http://www.thenagain.info/webchron/india/Harappa.html
Scholarly Summary
http://www.harappa.com/har/indus-saraswati.html
Excavation Reports (1986 - 1990)
http://www.harappa.com/harappa_1986_1990/harappa-excavation-reports.html
The date 2600 BC is now considered to mark the approximate beginning of the major integration of urban polities, the use of writing, weights, Harappan type ceramic designs, etc. (Kenoyer 39)
http://www.harappa.com/harappa_1986_1990/Harappa1986-90_04_Kenoyer-UrbanProcess.pdf
Undeciphered Script