![[The_drainage_system_at_Lothal_2.jpg]] *Remains of the drainage system at Lothal.* Unlike Egypt and Uruk, which both relied on single-season cereal cultivation, Indus Valley people developed a multi-cropping system that allowed them to plant wheat and barley in the winter and millet, rice, and legumes in summer. Rotating crops and using fields year-round allowed Mohenjo-Daro to grow to about 60,000 and Harappa to reach 40,000 by about 4,500 years ago. Several other less-well-known cities may have reached similar sizes. ![[Lothal-layout-en.svg.png]] The Indus Valley Civilization maintained an extensive trade network both over land and from port cities such as [Lothal](https://en.wikipedia.org/wiki/Lothal#). The brick-lined dockyard at Lothal was protected from the tides by a lock-and-gate system that facilitated loading and unloading cargoes. Trade partners included Mesopotamia (from whom they bought silver, tin, copper, and woolen textiles), the Persian Gulf (copper, pearls), and Central Asia (lapis lazuli, turquoise, pottery, tin). The Indus culture established a uniform system of weights and seals, which helped standardize trade. Lothal's trade surpluses supported craft specialization and urbanization during a peak period that began about 4,600 years ago, until a weakening of the monsoon degraded the harbor, disrupted trade and ultimately cause the civilization's major cities to be abandoned by 3,900 years ago. ![[Dock_at_lothal.jpg]] ----- Next:[[3.10 - Longshan]] Back: [[3.8 - Indus Valley]]