Mohenjo Daro Flourishing around 2000 B.C.E., Mohenjo Daro was by far the largest city of the Indus Valley civilization, covering more than 600 acres. This photograph shows a small part of that city as it has been uncovered by archeologists during the past century. The large watertight tank or pool, shown in the foreground, probably offered bathers an opportunity for ritual purification. (View of the Great Bath/Luca Tettoni/Bridgeman Images)