The Indus Valley Civilization was one of the world's earliest urban cultures, flourishing around 2500 BCE in what is now Pakistan and northwest India. Known for its advanced city planning, the civilization featured well-organized streets, sophisticated drainage systems, and impressive architecture, including the famous city of Mohenjo-Daro. This civilization was remarkable for its trade networks and use of standardized weights and measures. The people of the Indus Valley engaged in agriculture, crafts, and trade, contributing to a vibrant economy. Despite its achievements, the reasons for its decline around 1900 BCE remain a mystery to historians.