Post 1980 studies indicate that food production was largely indigenous to the
Indus Valley. It is known that the people of Mehrgarh used domesticated wheats
and barley and the major cultivated cereal crop was naked six-row barley, a crop
derived from two-row barley (see Shaffer and Liechtenstein 1995, 1999).
Archaeologist Jim G. Shaffer (1999: 245) writes that the Mehrgarh site
"demonstrates that food production was an indigenous South Asian phenomenon" and
that the data support interpretation of "the prehistoric urbanization and
complex social organization in South Asia as based on indigenous, but not
isolated, cultural developments."
Indus civilization agriculture must have been highly productive; after all, it was capable of generating surpluses sufficient to support tens of thousands of urban residents who were not primarily engaged in agriculture. It relied on the considerable technological achievements of the pre-Harappan culture, including the plough. Still, very little is known about the farmers who supported the cities or their agricultural methods. Some of them undoubtedly made use of the fertile alluvial soil left by rivers after the flood season, but this simple method of agriculture is not thought to be productive enough to support cities. There is no evidence of irrigation, but such evidence could have been obliterated by repeated, catastrophic floods.
The Indus civilization appears to contradict the hydraulic despotism hypothesis of the origin of urban civilization and the state. According to this hypothesis, all early, large-scale civilizations arose as a by-product of irrigation systems capable of generating massive agricultural surpluses.
It is often assumed that intensive agricultural production requires dams and canals. This assumption is easily refuted. Throughout Asia, rice farmers produce significant agricultural surpluses from terraced, hillside rice paddies, which result not from slavery but rather the accumulated labor of many generations of people. Instead of building canals, Indus civilization people may have built water diversion schemes, which - like terrace agriculture - can be elaborated by generations of small-scale labor investments. It should be noted that only the easternmost section of the Indus Civilisation people could build their lives around the monsoon, a weather pattern in which the bulk of a year's rainfall occurs in a four-month period; others had to depend on the seasonal flooding of rivers caused by snow melt at high elevations.