When you read a list of the earliest civilizations and places that had a very early writing system, you'll see Harappa and the still mysterious Harappan culture, which are named after a leading town on the Indian subcontinent, in the Punjab. The two leading centers were Harappa and Mohenjo-Daro.
From 2500 B.C. to 1600 B.C. the Indian subcontinent was dominated by Harappan Culture. The Harappan Culture had writing especially on cylinder seals, complex social and economic systems, showed signs of urban planning with east west and north south street grids, and water supply and drainage, including bathroom and latrine facilities in some houses. Archaeologists have found skilled sculpture, inscribed seals, and possible evidence of trepanation [See: "Religious Healing in the Veda," by Kenneth G. Zysk; Transactions of the American Philosophical Society, New Series, Vol. 75, No. 7 (1985) , pp. i-xv, xvii, 1-311]. Their urban culture relied on an agrarian subculture. The Harappan Culture rose along the Indus River Valley.