Sri Vaishnav Sampradaya or Sri Vaishnavism is a Vaishnava sect within Hinduism, dedicated to the worship of the Vedic Supreme Being Vishnu. Vishishtadvaita Vedanta is it's philosophy. Its origin and codification is generally traced back to the goddess Lakshmi (Sri), the consort Vishnu and is the oldest among the four original Vaishnava sampradayas mentioned in the Padma Puran. Around the 10th century a collection of the devotional hymns and songs by Alvars was organized by Nathamuni, who is considered to be one of the pioneers of the sect. Nathamuni wrote Sanskrit works systematizing the Sri Vaishnava theology, largely in debate with the philosophy of Buddhism. He was followed by Yamunacharya, a celebrated grand-teacher of Ramanujacharya. Yamunacharya, like Ramanujacharya, focused both on philosophical debates like dvaita versus advaita and bhakti prayers and the works attributed to him are in Sanskrit although he codified the heritage of the Alvars.In this tradition, Vishnu is believed to be the Supreme Being and the source of all avatars. The Iyengar Brahmins are followers of Ramanuja sampradaya, and two sects, namely Vadakalai and Thenkalai exist among them. They believe in the philosophy of Visishtadvaita espoused by Ramanujacharya.