Final answer:
The bitumen used in Mohenjo-Daro likely came from trade with regions such as modern-day Iran and Central Asia. The Indus Valley Civilization was part of a vast trade network that included the import of materials necessary for their advanced urban constructions, including bitumen for waterproofing purposes.
Step-by-step explanation:
The bitumen used to waterproof important structures in Mohenjo-Daro and other cities along the Indus most likely came from trade exchanges with neighboring regions, particularly from the areas that are modern-day Iran and Central Asia. Bitumen, a substance often used for waterproofing and as an adhesive, was a material available in these regions and known to have been used by various ancient civilizations.
The Indus Valley Civilization was renowned for its urban planning and architecture, including advanced drainage systems and public baths like the Great Bath at Mohenjo-Daro. The civilization was part of an extensive trade network that connected it to Mesopotamia and other regions. Archaeological evidence indicates that materials like precious stones and marine shells from the Indian Ocean were imported. Such trade networks likely allowed the Indus Valley cities to acquire bitumen for construction purposes.
The historical and archaeological record suggests that these complex societal needs and commercial activities facilitated the acquisition of resources like bitumen, which were not indigenous to the Indus valley but were integral to their technological advancements and urban development efforts.