Many of the largest Indus cities were continuously occupied from the Early Harappan through the Harappan period. Consequently, the Harappa phase buildings and city walls often rose high above the surrounding plain, being constructed on top of earlier buildings and city walls. In some settlements, new suburbs were constructed out on the plain or on old city dumps, resulting in a higher older town and a lower newly built areas. At sites such as Harappa and Kalibangan, two distinct walled areas or mounds were created, and at other sites such as Mohenjo-daro, several different mounded areas were established.
The landscape was dominated by large cities located at strategic positions along trade routes and in the core area of agricultural production. Mohenjo-daro, Harappa, Rakhigarhi, and Dholavira are major cities, all of which are over 100 ha in area. Ganweriwala may represent a fifth major city at around 80 ha in area. The actual size of a settlement would have changed considerably over 700 years, but based on surveys of mounded ruins it is possible to identify an hierarchy of five settlement tiers: cities (greater than 80 ha), towns (10-50 ha), villages (5-10 ha), and hamlets (1-5 ha), camps (<1ha). In addition, many people may have lived in floating villages or along the many rivers and lakes that surrounded the major cities.
Over 1500 sites have been identified from this time period located in many different geographical regions, including coastal areas, alluvial plains, and remote mountain valleys. Estimates of the total area of the Indus civilization range from 680 000 to as much as 800 000 km2, but it should be clearly understood that there were large stretches of uninhabited wasteland between many of the sites and the total area does not represent a territory of centralized political control or one that has distinct boundaries.
Population estimates for the Indus period are difficult to determine, because it is not possible to accurately define how much of a city was occupied at any given time or which settlements were inhabited during the 700-year time span of the Harappa phase. The site of Harappa, which covers around 150 ha, could have held between 60 000 and 80 000 people at the height of the urban phase, but the total urban population may have fluctuated seasonally. Nomads and merchants may have come to the city during trading seasons, and many urban dwellers may have left to help in the fields during the agricultural or herding seasons.
World History
