The Indus Valley Civilization was one of the earliest urban civilizations that flourished between 3300-1300 BCE along the Indus River valley. Two major cities, Mohenjo-Daro and Harappa, were centers of this advanced civilization, which engaged in extensive trade, used wheeled vehicles and sea-faring craft, and developed a sophisticated system of weights, measures, and an as yet undeciphered writing system. The Indus Valley people practiced agriculture and domesticated crops like wheat and barley. Remains also provide evidence of well-developed arts and crafts.