(Sanskrit: Vajrayāna, the ‘diamond or thunderbolt vehicle.’) A form of esoteric Mahayana associated with Tantra, and therefore distinct especially by virtue of its rituals and methods. Sometimes it is called Mantrayana (Mantrayāna), ‘the mantra vehicle’. In English-speaking contexts, it is often simply called ‘Tibetan Buddhism’. Originating in the north-east of the Indian subcontinent, today it is predominant in Tibet, Bhutan, Mongolia, and parts of Nepal, though it was historically influential also in Japan and Southeast Asia.