Information regarding India ’s climate dates back for thousands of years. The reason for this is that India was once ruled by the empire of Alexander the Great in 300 B.C. Alexander’s empire was one of the first western civilizations to keep environmental and meteorological records in writing. Thus, from just about the western world’s beginning, India ’s environmental records have existed in writing.
However, although no written documents regarding India’s weather and climate exist prior to Alexander’s era, we can assume certain climatic conditions and changes prior to 300 B.C. due to the known history of native civilizations that previously existed. Between the years 2500 and 1700 B.C., the Indus valley in the northwest portion of today’s India fostered homes for great civilizations. Around the cities of Harappa and Mohenjodaro large civilizations flourished. In order to understand why such great civilizations existed in the Indus valley during this period, it is essential to understand the climatic conditions that existed there at the time and whether or not the fall of these civilizations correlated with any climatic changes. When examined closely, it is quite evident that the Indus valley was home to great civilizations between 2500 and 1700 B.C. directly as a result of the abundance of water in the region. Furthermore, the decline of these civilizations and the absence of any such great civilizations existing shortly thereafter is a direct result of the continual lessening amounts of water for the millennium to follow.
Between 2500 and 1700 B.C., the Indus valley had an annual rainfall of 400 to 800 mm. This annual rainfall was the ideal amount of water needed for this specific region to harbor great civilizations. Prior to 2500 B.C., the Indus valley was home to massive flooding periods that existed for up to a century at a time. This period, between 3500 B.C. and 3000 B.C. was known as the ‘sub-Boreal’ climatic period. (Lamb, pg. 130). It can be concluded, therefore, that the rise of the Indus valley civilizations around 2500 B.C. was a result of ideal agricultural conditions left behind from a century to century cyclical flood period. Naturally, this flooding cycle did not continue past 2500 B.C. because it would have destroyed agriculture for these civilizations for as long as the floods lasted, which could have been as much as a century at a time.
Ironically, whereas the development of great civilizations was hindered from an abundance of water prior to 2500 B.C., the decline of the Indus valley’s civilizations after 1700 B.C., was due to a lack of water. After 1900 B.C., the Indus valley entered a period of extended drought, bringing the Indus valley civilizations to their demise. From the climatic information that we have, it seems as if this drought continued for over 1,000 years.
As future civilizations conquered this area, it has been concluded from remaining documentation that the Indus valley never again hosted...