Indian philosophy refers to ancient philosophical traditions (; 'world views', 'teachings') of the Indian subcontinent. Jainism may have roots dating back to the times of the Indus Valley Civilization. The major orthodox schools arose sometime between the start of the Common Era and the Gupta Empire. These Hindu schools developed what has been called the "Hindu synthesis" merging orthodox Brahmanical and unorthodox elements from Buddhism and Jainism. Hindu thought also spread east to the Indonesian Srivijaya empire and the Cambodian Khmer Empire. These religio-philosophical traditions were later grouped under the label Hinduism. Hinduism is the dominant religion, or way of life, in South Asia. It includes Shaivism, Vaishnavism, and Shaktism among numerous other traditions, and a wide spectrum of laws and prescriptions of "daily morality" based on karma, dharma, and societal norms. Hinduism is a categorization of distinct intellectual or philosophical points of view, rather than a rigid, common set of beliefs. Hinduism, with about one billion followers is the world's third-largest religion, after Christianity and Islam. Hinduism has been called the "oldest religion" in the world and is traditionally called "Sanātanī", "the eternal law" or the "eternal way"; beyond human origins. Western scholars regard Hinduism as a fusion or synthesis of various Indian cultures and traditions, with diverse roots and no single founder.