The ancient civilization that developed along the Indus River was the Indus Valley Civilization, also known as the Harappan Civilization. This civilization flourished from approximately 2600 to 1900 BCE in what is now modern-day Pakistan and northwest India. The Indus Valley Civilization is known for its advanced urban planning, sophisticated drainage systems, and standardized weights and measures. Major cities like Harappa and Mohenjo-Daro displayed remarkable architectural innovations and evidence of trade with neighboring regions. The decline of this civilization remains a topic of research, with theories suggesting environmental changes, social upheaval, or shifts in trade routes.