Tibetan Buddhism is the body of religious Buddhist doctrine and institutions characteristic of Tibet and the Himalayan regions which include northern Nepal, Bhutan, India (Arunachal Pradesh, Ladakh and Sikkim), Mongolia, Russia (Kalmykia, Buryatia and Tuva) and northeastern China (Manchuria: Heilongjiang, Jilin). It includes the teachings of the three vehicles (or yanas in Sanskrit) of Buddhism: Hinayana, Mahayana, and Vajrayana[1]. The occupation of Tibet by the People's Republic of China in 1959, which resulted in the Tibetan diaspora, eventually led to the spread of Tibetan Buddhism to many Western countries where the tradition has gained great popularity. In the past, Tibetan Buddhism was referred to by some westerners as "Lamaism" but this is now considered by many to be based on a misunderstanding of the practice of guru yoga ('guru' is the Sanskrit equivalent of the Tibetan word 'lama' which means 'spiritual teacher') in Tibetan.