The ancient civilization that developed a complex caste system in society was the Indus Valley Civilization, particularly in the context of the later Indian society and the Vedic period. The caste system, which categorized individuals into rigid social hierarchies based on occupation and birth, can be traced back to ancient texts known as the Vedas. This system divided society into four main groups: Brahmins (priests), Kshatriyas (warriors), Vaishyas (traders), and Shudras (laborers). It influenced social interactions, economic opportunities, and religious practices for centuries, shaping India's cultural and societal structure, causing profound social implications still relevant today.