The Indus Valley civilization developed advanced agricultural techniques using irrigation systems and tools like the plow. They grew many crops at a large scale. Sports in the Indus Valley involved weapons used for hunting and warfare to develop strategic thinking. Cities were carefully planned and constructed using unique building strategies. The civilization started as farmers moved between mountain homes and river valleys, related to sites identified in the Ghaggar-Hakra River Valley. The Indus Valley religion was polytheistic with influences from later Hinduism, Buddhism, and Jainism. Some seals depict gods like Shiva and Rudra. The civilization declined possibly due to changes in geography and climate, including flooding and shifts of the Indus River.