The spiritual traditions of Tibet began with the early Bon religion of the Zhang-zhung kingdom. Buddhism was introduced to Tibet through various political and cultural contacts and was eventually established as the state religion by King Tri Songdetsen in the eighth century CE. Following the Samye debate, the Tibetan empire officially favored the gradual approach of Indian Buddhism, based on analytical meditation, over the sudden enlightenment approach of Chinese Chan Buddhism. Although King Langdarma severely suppressed Buddhist monastic institutions in the ninth century, Buddhist practices continued privately and underwent a major revival during the New Translation Period. This revival led to the formation of the four major Tibetan Buddhist traditions – Nyingma, Kagyu, Sakya and Gelug – alongside the revival and synthesis of the Bon tradition. Although these Buddhist traditions share a common foundation in the Indian Mahayana sutras and tantric practices, they differ in certain philosophical interpretations, such as those concerning the ultimate nature of the mind and other-voidness. Tibetan Buddhism developed into a distinctive intellectual tradition, employing skillful means to incorporate various Central Asian influences into a spiritual system adapted to Tibetan circumstances.