centuries fully flourished in urban centers. Due to the high quality of its arts, crafts, metallurgy and buildings, the accomplishments in urban planning, governance, trade and technology etc. it has been classified as one of the principal Cradles of civilization. Referred to as the Indus Valley civilisation or Harappan Civilisation it thrived for almost 2.000 years until the onset of the Vedic period (c. 1500 – c. 600 B.C.). The great significance of the Vedic texts (that don't mention cities or urban life) for South Asian culture, their impact on family, societal organisation, religion, morale, literature etc. has never been contested. The Indus Valley Civilisation on the other hand has only come to light by means of 20th century archaeology. Scholars, who employ several periodization models argue over whether South Asian tradition is consciously committed to the Harappan culture. Declining climatic conditions, (aridification) and population displacement (Indo-Aryan migration) are regarded as to have caused the fatal disruption of the Harappa culture, that was superseded by the rural Vedic culture. Following the Indo-Aryan settlement in the Indo-Gangetic Plain and the establishment of the characteristic social groups (Brahmanas, Kshatriyas, Vaishyas and Shudras) in the caste system based on the Jāti model in the Varna order, the tribal entities variously consolidated into oligarchic chiefdoms or kingdoms (the 16 Mahajanapadas), beginning in the sixth century B.C. The late Vedic political progress results in urbanization, strict social hierarchy, commercial and military rivalries among the settlers, that have spread all over the entire sub-continent. The large body of Vedic texts and literature, supported by the archaeological sequence allows researchers to reconstruct a rather accurate and detailed image of the Vedic culture and political organisation. The Vedas constitute the oldest work of Sanskrit literature and form the basis of religious, ethic and philosophic ideas in South Asia. They are widely, but not exclusively regarded the basics and scriptural authority on worship, rituals, ceremonies, sacrifices, meditation, philosophy and spiritual knowledge for the future Hindu and Buddhist cosmology. Commentaries and discussions also focus on the development of valid political ideas and concepts of societal progress and ethic conformity. Hinduism, Buddhism, Jainism and Sikhism are major religions of South Asia. After a long and complex history of cosmological and religious development, adoption and decline, the Hindu-synthesis and the late but thorough introduction of Islam about 80% of modern-day Indians and Nepalis identify as Hindus. In Sri Lanka and Bhutan most