This article investigates the agricultural practices that supported the rise of the Indus civilization by focusing on summer and winter crops used at settlements in the Rakhigarhi, Haryana area, particularly Masudpur VII and Masudpur I. It provides the first direct radiocarbon dates for the cultivation of summer crops such as rice, millet, and tropical pulses by Indus populations, challenging prior assumptions about the subsistence practices of this civilization. Most importantly, these investigations and dating provide evidence of multi-cropping systems involving both winter and summer crops, which likely played a significant role in sustaining urban centers like Rakhigarhi. This is the larger issue – understanding how urban civilizations arose and were supplied. According to current widely-accepted theories, this happened in tandem with agriculture simply because large agricultural surpluses were needed to keep city dwellers who did not grow food alive and kicking.

A key finding is that Indus people in the Rakigarhi area cultivated rice, which hitherto had been thought of as a post-Indus civilization crop to the east in the Gangetic plain. Rice is a summer crop, and as the authors show, it suggests that crop strategies evolved in response to environmental and climatic conditions in Indus times, contributing to both urban and rural subsistence (rice, for example, does not seem to have been cultivated some 350 kilometers to the west at Harappa). A re-evaluation of the role of rice in the Indus economy, particularly given the evidence of its use earlier than traditionally believed, is one consequence of the research behind this article.

The discovery that these communities employed diverse agricultural strategies like mixed cropping also suggests that there was no uniform approach across the entire Indus zone (see image above). Different areas adapted to local environmental conditions. Food production and provisioning in the Indus civilization were more complex and regionally varied than previously thought; it also points to the fortitude of Indus farmers and what would have been a complex planting and transportation system between regions to move harvested items to where they were needed. Future studies, once we have a a more complete picture of crop strategies in different regions (and urban population sizes) could explore how these agricultural systems influenced the social and economic organization of Indus cities and rural settlements and their relationships. How did the adoption of rice and summer crops in the Indus civilization influence its urbanization processes and the growth of major cities like Rakhigarhi?

Another question to ask is to what extent did agricultural practices in different regions of the Indus civilization reflect environmental adaptation versus cultural choices? We may not know yet, and while the former is critical, given the human agency directly involved in wrestling the crops from the land, there would also have been cultural, social, even religious factors involved in what people in different areas did. Understanding the balance between environmental necessity and cultural preference could shed light on agricultural decision-making across the civilization - was it centralized to any extent? How were shortages handled if crops failed in one area? Did surplus crops from multi-cropping regions support areas with less agricultural diversity, contributing to economic interdependence within the Indus region? The excellence of the research leads to questions, which while not yet answered, are given more credence and urgency with data now so nicely gathered and presented.

The authors conclude: "This South Asian example demonstrates diversity in the underlying environmental, climatic and geographic contexts of the Indus civilisation, and variation in the crops being used in different regions, which in turn appears to have promoted diversity in the approaches to subsistence used by populations occupying different parts of the landscape. The subsistence practices of the Indus civilisation therefore make a unique and important contribution to our understanding of the rise of early socio-economic complexity and urbanism," (p. 1501).

Images: The region across which Indus-period settlements are distributed, with the distribution of modern winter and summer rainfall indicated. Precise rainfall distribution patterns during the Middle Holocene are as yet unclear (see OSM 1). Map generated using NASA Blue Marble: Next Generation satellite imagery, which was produced by Reto Sto ̈ckli and obtained from NASA’s Earth Observatory (NASA Goddard Space Flight Center). See: http://earthobservatory.nasa.gov/ Features/BlueMarble/. Rainfall distribution data were extracted from the University of Delaware’s monthly global gridded high-resolution station (land) dataset of precipitation from 1900–2008 (v2.01) by D.I. Redhouse using GDAL/OGR41. Map prepared by C.A. Petrie using ArcMAP 10.2. Data available from: http://www.esrl.noaa.gov/psd/data/gridded/data. UDel AirT Precip.html.