Archaeologists like Sir Mortimer Wheeler and Stuart Piggott believed that the Harappan towns had a remarkable unity of conception. The entire ideal of unity of conception was derived from the notion of a community of foreigners suddenly conquering the Indus Valley and building new towns.
Such towns were designed to separate the natives from the rulers. However, more recent researchers reject the theory of the sudden emergence of the Harappan towns and unity of planning.
According to them, the city culture emerged out of local settlements in the Indus region. The Harappan towns were located on the floodplains of rivers, on fringes of deserts or on the sea-coast which meant that people living in these different regions faced different kinds of challenges from nature.
Their adaptation to environment introduced diversity in their town-planning and life-style too. In Mohenjo-daro and Harappa, the citadel was surrounded by a brick wall.
At Kalibangan, both the citadel and the lower city were surrounded by a wall; streets ran from north to south in the lower city and cut at right angles. Although the alignment of streets and buildings represents conscious town planning, there were considerable variations too.
The site of Lothal was a rectangular settlement surrounded by a brick wall with no internal division into citadel and lower city. In settlements like Kot Diji and Amri there was no fortification of the city.
Baked bricks were used for buildings in Harappa and Mohenjo- daro; in Kalibangan, mud bricks were used. That baked and unbaked bricks of standard size were used throughout, suggests that brick-making was organised on a large scale.
Another feature of cities like Mohenjo-daro was the excellent arrangements for sanitation, made possibly by a common civil administration. The waste water from houses would pass through chutes connected with public drains aligned to the margin of the streets.
Scholars call the period 3500-2600 BC as the early Harappan period because they believe that this was the formative epoch of the Harappan civilisation when certain trends of cultural unification were in evidence.
Excavations at Mehrgarh (in Sindh)-the earliest known cultivating centre in South Asia-have yielded stray pieces of copper, artefacts like few seals, and copper-stained crucibles, dating around or before 9000 BC. A quantity of pots had been stacked near a kiln. It suggests the advent of the village potter.
The village was now the largest of all its contemporaries in Quetta valley. That Mehrgarh was the largest of the villages is not explained by craft production because all craftwork is not necessarily specialized work.
However, it was the Karachi plain, where Mehrgarh was located, which saw the maximum pastoralist ingress in the winter months. The relationships between mobile herders and settled cultivators provided the maximum scope for the development of new social institutions.
Mundigak in southern Afghanistan, apparently located on a trade route, grew into a large township. A palace, a temple, a variety of pottery, the use of naturalistic decoration, terracotta female figurines and semi-precious stones as lapis lazuli and steatite have been found.
The use of lapis lazuli and steatites indicates a close relationship between Iran and Central Asia because these stones were not locally available. At Damb Sadat in Quetta valley, large houses having brick walls belonging to the beginning of the third millennium BC have been discovered.
People of the central and southern Baluchistan sites like Anjira, Togou, Ninduwari and Balakot were using similar kinds of pottery showing distinct influences from both the Persian-Gulf towns and the Indus Valley towns.
By the middle of the fourth millennium BC, the Indus alluvial plains became the focal point of change. The banks of the Indus and Ghaggar-Hakra saw the emergence of many settlements.
People of Amri in the Sind province lived in houses of stone and mud brick, constructed a granary of sorts, and painted animal motifs as the humped Indian bull on their pottery which was wheel-made.
People of Kot Diji, opposite Mohenjo-daro, had a massive defensive wall built around their settlement. They also used a wheel-thrown pottery having decorations of plain bands of dark brownish paint, a variety found along the entire stretch of River Indus, where Harappan settlements have been reported.
At Rahman Dheri, an Early Indus township has been excavated. Oblong in shape, with houses, streets and lanes laid out in a planned fashion, it is protected by a massive wall.
At Kalibangan, in north Rajasthan, a remarkable find was that of a ploughed field surface, suggesting