Trade and transport
The Indus civilization's economy appears to have depended significantly on
trade, which was facilitated by major advances in transport technology. These
advances included bullock carts that are identical to those seen throughout
South Asia today, as well as boats. Most of these boats were probably small,
flat-bottomed craft, perhaps driven by sail, similar to those one can see on the
Indus River today; however, there is secondary evidence of sea-going craft.
Archaeologists have discovered a massive, dredged canal and docking facility at
the coastal city of Lothal.
During 4300 - 3200 BC of the chalcolithic period (copper age), the Indus Valley Civilization area shows ceramic similarities with southern Turkmenistan and northern Iran which suggest considerable mobility and trade. During the Early Harappan period (about 3200–2600 BC), similarities in pottery, seals, figurines, ornaments etc. document intensive caravan trade with Central Asia and the Iranian plateau.
Judging from the dispersal of Indus civilisation artifacts, the trade networks, economically, integrated a huge area, including portions of Afghanistan, the coastal regions of Persia, northern and central India, and Mesopotamia.
There was an extensive maritime trade network operating between the Harappan and Mesopotamian civilisations as early as the middle Harappan Phase, with much commerce being handled by "middlemen merchants from Dilmun" (modern Bahrain and Failaka located in the Persian Gulf). Such long-distance sea-trade became feasible with the innovative development of plank-built watercraft, equipped with a single central mast supporting a sail of woven rushes or cloth.
Several coastal settlements like Sotkagen-dor (astride Dasht River, north of Jiwani), Sokhta Koh (astride Shadi River, north of Pasni) and Balakot (near Sonmiani) in Pakistan along with Lothal in India testify to their role as Harappan trading outposts. Shallow harbors located at the estuary of rivers opening into the sea allowed brisk maritime trade with Mesopotamian cities.