The Indus River Valley civilization flourished between 3200-600 BCE. Some key aspects include: - The Harappan society built cities with grid patterns and advanced plumbing/sanitation systems. - They had powerful leaders and a well-organized government, and engaged in agriculture and trade. - Around 1500 BCE, Aryan groups invaded and the Indus civilization began to decline. The Aryans established Vedic civilization along the Ganges River. - Vedic society was stratified into castes including priests, warriors, merchants, peasants, and untouchables. Gender roles were also highly patriarchal.