Vajrayana is one of the major schools of Buddhism which originated in Gandhara (modern-day Pakistan). It is sometimes called esoteric Buddhism. Padmasambhava from Gandhara brought Buddhism to Tibet. It later spread to Mongolia and Bhutan. Since the annexation of Tibet by the People's Republic of China in 1959, the Tibetan form of Vajrayana has spread to many Western countries and has gained great popularity.