Ancient Indian civilization developed primarily along the Indus River, with notable cities like Harappa and Mohenjo-Daro showcasing advanced urban planning and social organization. The arrival of the Aryans around 1500 BCE significantly influenced the region's culture, leading to the emergence of Hinduism and the caste system, while Buddhism later arose from the teachings of Siddhartha Gautama. The Mauryan and Gupta empires later unified and prospered in India, fostering advancements in arts, sciences, and religious practices.