Environmental Change and the Indus Civilization

Osada Toshiki RIHN

Goto Toshifumi Tohoku University Kharakwal, Jeewan Singh Rajasthan Vidyapeeth, India Mallah, Qasid Shah Abdul Latif University, Pakistan Masih, Farzand Punjab University, Pakistan Maemoku Hideaki Hiroshima University Onishi Masayuki RIHN Ohta Shoji Fukui Prefectural University Shinde, Vasant Deccan College, Deemed University, India Uno Takao International Research Center for Japanese Studies

The Indus Civilization (2600 BC - 1900 BC) is one of the four great ancient civilizations. It is known for its cultural and technological achievements - its characteristic seals and scripts, fortified settlements and sewerage systems - and also for its brief tenure. The Indus civilization spread over an area of 680,000 km2 along the Indus and Ghaggar rivers and into Gujarat in Western India, but its urban phase lasted only 700 years, much shorter than any of its contemporaries. Drawing on archaeology, Indology, and paleo-environmental investigation, this project reconstructs the social and environmental histories of several Indus cities, and attempts to determine whether and how environmental factors contributed to their short life and rapid decline.

Project structure and objectives

This research project examines the social character and environmental context of the Indus civilization, and attempts to determine how they are related to the civilization's short life and rapid decline. In particular, we aim to evaluate the impact of environmental change on the subsistence economy and trade network that sustained the Indus civilization's urban system. Our research will also provide data on the long-term processes of climate change in South Asia. Such data will help us develop historical perspective on, and practical understanding of, contemporary environmental problems in the region.

Our project is divided into four research groups: (1) the Palaeo-Environmental Research Group (PERG); (2) the Material Culture Research Group (MCRG); (3) the Subsistence System Research Group (SSRG); and (4) the Inherited Culture Research Group (ICRG) (Fig. 1). They integrate cultural and biological data obtained from archaeological excavations and other field activities, palaeo-environmental data obtained from satellite imagery and field study, and original accounts obtained from ancient texts. Important subjects of study investigated so far include: ancient climate change; avulsion of the Ghaggar River; the palaeocoastline of Gujarat; and palaeo-seismic activity.

Major achievements

In 2009 our project achieved great advance in the study of the natural environment surrounding the Indus civilization. Most substantially, PERG successfully obtained sediment core samples from the Rara Lake in Nepal (Photo 1), which will allow us to reconstruct climate change in South Asia in the last 7500 years (Fig. 2).

PERG conducted field research and analysis of satellite imagery to identify the former course of the Ghaggar River (the old Saraswati River) and determine the causes and the dates of its avulsion. Contrary to its description in the Rig-Veda text (transliterated by ICRG), field evidence demonstrates that the Ghaggar was not a large river, but a small one capable of providing water for agriculture only during the monsoon season. This finding indicates that the Indus civilization was not as dependent as the three other great ancient civilizations on large rivers. MCRG analysis of archaeological artefacts from the Farmana site continues to improve our description of the Indus civilization resource base, society and economy.

Archaeological data obtained at the Kanmer site and geological and topographical data obtained through field research and satellite imagery are being combined to describe ancient sea level change along the coast of Gujarat. Simulation based on bathymetric data suggests that the Indus period sea level was about two meters higher than in present-day Gujarat. If correct, the ancient cities currently found inland would have earlier been located along the coast. We believe that these cities would have been an important base for trade with Mesopotamia. ICRG has been studying cuneiform texts for evidence relevant to our hypothesis.

Excavation at Farmana and Kanmer has concluded. The MCRG uncovered a number of important structures, artefacts, and plant and animal remains (Photos 2, 3), and analysis of these materials continues. Palaeo- and ethno-botanical research conducted by SCRG and philological research conducted by ICRG has allowed us to gradually reconstruct the ancient environment, subsistence systems and trade network of the Indus civilization. The geographical distribution of cultivated plants and archaeological sites during the Indus period (Fig. 3) suggests that climate change may have affected the monsoon pattern and triggered major agricultural change in the region.

The study of ancient sea temperatures through coral sampling in the Maldives and former monsoon rain temperature through the analysis of fossilized otoliths is also underway. In addition, a new study group was formed to conduct DNA analysis on the human bones discovered at the Farmana site.

Future activities

MCRG will continue analysing and preparing for publication the data obtained from excavations at Kanmer and Farmana. PERG will analyse the core samples obtained from the Rara Lake and Gujarat sites to reconstruct the palaeo-environment of Ghaggar and Gujarat regions. They plan to present their findings at the 2010 conference of the American Geophysical Union, and subsequently publish academic papers on climate change of ancient South Asia. SSRG will carry out pollen and phytolith analysis on data obtained from the excavations, while ICRG will continue its philological and linguistic research.