The International Society for Krishna Consciousness or ISKCON, known colloquially as the Hare Krishna movement or Hare Krishnas, is a Gaudiya Vaishnava Hindu religious organization. ISKCON was founded in 1966 in New York City by A. C. Bhaktivedanta Swami Prabhupada. Its core beliefs are based on Hindu scriptures, particularly the Bhagavad Gita and the Bhagavata Purana. ISKCON is "the largest and, arguably, most important branch" of Gaudiya Vaishnava tradition, which has had adherents in India since the early 16th century and American and European devotees since the early 1900s. ISKCON was formed to spread the practice of Bhakti yoga, the practice of love of God in which those involved (bhaktas) dedicate their thoughts and actions towards pleasing Krishna, whom they consider the Supreme Lord. Its most rapid expansion in membership has been within India and (after the collapse of the Soviet Union) in Russia and other formerly Soviet-aligned states of Eastern Europe. ISKCON devotees follow a disciplic line of Gaudiya Vaishnavas and are the largest branch of Gaudiya Vaishnavism. Vaishnavism means 'worship of Vishnu', and Gauḍa refers to the area where this particular branch of Vaishnavism originated, in the Gauda region of West Bengal and Bangladesh. Gaudiya Vaishnavism has had a following in India, especially West Bengal and Odisha, for the past five hundred years. Gaudiya Vaishnavism was founded by Chaitanya Mahaprabhu, who rapidly spread his form of ecstatic bhakti (devotion) throughout Bengal. He established Sankirtan, the practice of publicly expressing devotion to Krishna, the Supreme God, through dance and song. This form of communal worship responded to rigid caste structures by engaging all people in worship regardless of caste and creed. Sri Chaitanya Mahaprabhu emphasized chanting the Hare Krishna Mahamantra (the 'great mantra'). He is considered by Gaudiya Vaishnavas to be an incarnation of Krishna himself. Bhaktivedanta Swami Prabhupada, believed to have direct lineage with Chaitanya Mahaprabhu, brought Chaitanya's Gaudiya Vaishnavism to the West in 1965.