The Indus Valley Civilization (also known as Harappan culture) has its earliest roots in cultures such as that of Mehrgarh, approximately 6,000 BC. The two greatest cities, Mohenjo-Daro and Harappa, emerged Later c. 2,600 BC along the Indus River valley in Punjab and Sindh. (3) The architecture and city planning of Harappa was similar to that of Mohenjo-daro and the varieties of artifacts recovered from the excavations confirmed that these two sites represented the same cultural tradition which has come to be known as the Harappa Phase of the Indus Valley Civilization. (2)

They both planned the patterns of their cities, laying out streets in rectangular patterns and including drainage systems that led to brick-lined sewers. They lived in brick buildings, some two and three stories high. In almost every respect, they were an advanced people.

The first extensive excavations at Harappa were started by Rai Bahadur Daya Ram Sahni in 1920. His work and contemporaneous excavations at Mohenjo-daro first brought to the world's attention the existence of the forgotten Indus Valley civilization as the earliest urban culture in the Indian subcontinent.

The Harappa site was first briefly excavated by Sir Alexander Cunningham in 1872-73, two decades after brick robbers carried off the visible remains of the city. He found an Indus seal of unknown origin. His work was followed later in the decade by that of Madho Sarup Vats, also of the Archaeological Survery of India. M.S. Vats first excavated the "Granary," and published the results of his and Sahni's excavations in 1940. Excavations by other archaeologists continued in the 1930's, and in 1946 Sir Mortimer Wheeler excavated the so-called fortification walls and found the first pre-Indus Valley civilization (Kot Dijian) deposits.

 

Article: Nov, 2012 (GlobalPost.com):

'Archaeologists Confirm Indian Civillisation is 2000 Years Older than Previously suspected'

'Indian archaeologists now believe the ancient Indian civilisation at Harrapa dates back as far as 7,500 BC. �When Bhirrana [Rajasthan] was excavated, from 2003 to 2006, Recovered artefacts provided 19 radiometric dates,� said Dikshit, who was until recently joint director general of the Archaeological Society of India. �Out of these 19 dates, six dates are from the early levels, and the time bracket is forming from 7500 BC to 6200 BC.�

(Link to Full Article)

 

Excavations by the Harappa Archaeological Research Project have been able to build on these earlier studies to define at least five major periods of development starting at c. 3,300 Bc and lasting until c. 1,300 BC (2). They are defined in the following fashion:

3,300 BC - 'Ravi' Phase-

The earliest architectural structures at this time appear to have been huts oriented north-south and east-west made of wooden posts with walls of plastered reeds. Some mud-brick fragments of what may be a kiln have been found, but no complete mud-brick architecture has been found to date.

Pottery: The potters wheel became used towards the end of this phase. The use of pre-firing "potter's marks" and post-firing "graffiti" on pottery also indicates that concepts of graphic expression using abstract symbols were emerging. Many of the marks and signs consisted of a single character or symbol, but one example has three linked trident or plant shapes. Many of marks and signs used during the Ravi Phase continued to be employed through the Kot Diji Phase, and on into the Harappa Phase, where some of them can be identified as elements of the Indus writing system.

2,800 BC - 'Kot Diji' Phase -

The wide variety of raw materials used in specialized crafts during the Kot Diji Phase indicates the continued expansion of trade networks that were initiated during the Ravi Phase. Marine shells were brought from more than 860 kilometers away for ornament manufacture. Various rocks and minerals were imported over distances of 300 to 1000 kilometers for the production of utilitarian objects such as grinding stones and chipped stone tools as well for the manufacture of ornaments such as beads and inlay

Of particular importance at this time is the first appearance of the Early Indus script that has been found on pottery, a sealing of a square seal with possible Early Indus script, and a cubical limestone weight that conforms to the later Harappan weight category. In 2000 a fragment of an unfinished square steatite seal carved with an elephant motif was discovered which indicates that this unique type of seal was being made in addition to the more common geometric button seals (Meadow, Kenoyer and Wright 2000). These discoveries suggest that the development of the Indus script, the use of inscribed seals and the standardization of weights occurred during the Kot Diji period, some 200 years earlier than previously thought. The emergence of writing, seals and standardized weights also implies the development of more complex social and political organizations that would have required these sophisticated tools and techniques of communication and administration.

2,600 BC 'Harrapan' Phase -

The overall size of the city at this time was over 150 hectares.

This phase is marked by the greatest variation and widespread use of such seals appears to be during Period 3B. Small rectangular inscribed tablets made from steatite begin to appear at the beginning of Period 3B and by the end of 3B there is a wide variety of tiny tablets in many different shapes and materials. They were made of fired steatite or of moulded terracotta or faience. Some of the steatite tablets were decorated with red pigment and the faience tablets were covered with a thick blue-green glaze.