Certain of sects of Tibetan/Vajrayana Buddhism may have been influenced by Tantric teachings, a secret, esoteric pre-Buddhist shramana/yogi spirirual sect popular in the North India-Himalayana regions during early centuries ADs. Among popular Tantric teachings are the practice of Kundalini - Chakra chanels opening - meditation, secret spiritual initiation and some practices that put emphasis on transforming sexual energy that involves sexual intercourse between man and woman. The Tantric doctrines that are adopted by Hinduism (Brahmanism) may have some differences than those adopted by the later schools of Buddhism, such as the Tibetan Buddhism.