Vajrayāna is a form of Buddhism that evolved out of Mahāyāna during the 7th or 8th century in India. The name means ‘the Diamond Way’ and refers to the supposedly unbreakable logic Vajrayānists use to support their interpretation of the Dhamma. It is also sometimes called Tantrayāna, tantras being esoteric religious texts, or Mantrayāna, because of the importance it gives to the use of mantras. Vajrayāna spread to Sri Lanka, Burma, Thailand and China but eventually died out in all these places. Today Vajrayāna Buddhism is practised in Japan, where it is called Shingon, in Mongolia, Tibet, Bhutan and in some areas in the Indian Himalayas. Of late, Tibetan Vajrayāna has become very popular in the West, due to the influence of the Dalai Lāma and many Tibetan monks teaching there.