The Indian civilization dates back to 3200 B.C.

Remnants of this civilization are found in Mohenjodaro and Harappa, both in present day Pakistan. Later excavations revealed that the similar culture extended from Makran coast of Baluchistan in the West to Meerut in the Northeast which covered parts of Jammu, Kashmir, Punjab, Harayana, Sindh, Gujarat, Rajasthan and Maharashtra forming a triangular, comprising 1,299,600square kilometers --the largest civilization in the world. It is also the earliest civilizations of the world as is proved by certain scientific researches in Plant-Genetics accordingly, Punjab in India had the early start of civilization to commence agriculture & grow the food required to sustain the civilization. [Ref: Hindu Civilization, Radha Kumud Mukharjee p-43]. 

The finds from the site revealed that the culture was chalcolithic , the people used both stone as well as metals such as bronze and copper. 

It contained all the features of urban life. 

Some of the salient features discovered are listed below.

• The discovery of variety of seals proved the knowledge of writing, though efforts are made to decipher them but not been possible. Seals reveal the religious beliefs of the people and the means to note down the business transactions which facilitated trade & commerce with other countries.
• Town planning, with a citadel (fort)-dwelling place for ruling class with strong fortifications, below that houses for common people, then a market place, kilns & furnaces to manufacture burnt bricks were found outside the city along with city's drain water getting released into the fields, thus keeping the city clean.
• Sufficient water supply, a well for every house, public baths, both in working condition
• Good under ground drainage system, made possible due to the knowledge of arch, confirming geometrical knowledge of the people.
• Decent houses with amenities of bath, lavatory, water supply & a courtyard for pounding, grinding, laundry etc.
• Good roads cut each other at right angles dividing the city into blocks, roads were so arranged that the wind would work as suction pump, cleaning the area automatically
• The lamp posts lit the roads at night.
• Granary is another special feature of this civilization, used as a storage for future use or for collection of tax collected in kind,
• Existence of water proof great bath meant for ritual bathing, with an arrangement of exit of dirty water & pumping fresh water in the pool,& changing rooms
• Flourishing trade in precious stones like lapislazuli; metals like copper; as well as ivory, peacocks, apes (medical purpose), and shells with Mesopotamia, Egypt, and Central Asia. The finding of Indus seals in Egypt, Mesopotamia & the cuneiform tablets in the Indus valley & the existence of a dockyard in Lothal an important port in Gujarat prove the trade contacts.
• Highly standardized weights also an important characteristic of this urban civilization.

This spectacular valley civilization came to an end due to various reasons paving the way for the Aryan civilization in about 1800BC. 

The decline might have been due to flooding, tectonic movements causing silting, changing of the course of the rivers making the irrigation impossible, decrease in rains, environmental imbalance due to the over exploitation of forests or burning of bricks, pestilence etc. Earthquake also might have been one probability. According to some new research (called palio-pathology) the outbreak of viral disease might have caused death of most of the population, ending the civilization.