Tibetan Buddhism is the body of religious Buddhist doctrine and institutions characteristic of Tibet, the Himalayan region (including northern Nepal, Bhutan, Sikkim and Ladakh), Mongolia, Buryatia, Tuva and Kalmykia (Russia), and northeastern China (Manchuria: Heilongjiang, Jilin). It includes the teachings of the three vehicles (or yanas in Sanskrit) of Buddhism: Hinayana, Mahayana, and Vajrayana (also known as Tantrayana). The invasion and occupation of Tibet by China in 1959 (which has become known as 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 as "Lamaism" (See Lama) but this is now considered by many to be based on a misunderstanding of the practice of guru devotion ('guru' is the Sanskrit equivalent of the Tibetan word 'lama' and means 'spiritual teacher') in Tibetan Buddhism. Tibetan Buddhists generally find the term "lamaism" offensive.