The Vaishnavite tradition is known for the loving devotion to an avatar of Vishnu (often Krishna), and as such has been key to the spread of the Bhakti movement in South Asia in the 2nd millennium CE. Key texts in Vaishnavism include the Vedas, the Upanishads, the Bhagavad Gita, the Pancaratra (Agama) texts, Naalayira Divya Prabhandham and the Bhagavata Purana.