The Upanishads, originally written during 5th century BC and first translated into English in early 19th century, are early philosophical texts of the Hindu religion and contain within them the tenets upon which the central philosophical concepts of the religion are based. A doctrine on Hindu thought and culture and perhaps the most important literature from ancient India, The Upanishads expound on principles like samsara, brahman, atman, karma, dharma and moksha and form the core of Indian philosophy. Along with the Bhagavad Gita and the Brahmasutra, the Upanishads provide a foundation for the several later schools of Vedanta.