The document summarizes the Indus Valley Civilization, one of the three oldest civilizations in the ancient world. It discusses the geography and timeline of the civilization, revealing aspects of its urban planning, sanitation systems, arts, religion, and eventual decline around 1800 BCE. The causes of the decline are unknown but may have included drought or the arrival of the Aryans. Regional cultures emerged in the aftermath, blending with Vedic traditions, and the region later came under the control of successive empires until the arrival of Islam in 712 CE.