Yamunacharya also known as Alavandar and Periya Mudaliar was a Vishistadvaita philosopher in Srirangam, Tamil Nadu, India. Ramanuja, one of the leaders of the srivaishnava school sought to be his disciple. He was born in early 10th century CE and was the grandson of a Brahmin, Nathamuni. Nathamuni was a famed yogi who collected the works of Tamil alvars.
He grew up learning Vedic texts from Rama Misra also known as Manakkal Nambi and was skilled in mimansa. SriVaishnavite legend relates this history—As a teenager he challenged the royal priest Akkiyalvan of the Pandya king (the name of the king is disputed). Akkiyalvan, when he saw the age of the youth, asked sarcastically "alavandara?" meaning "has he come to rule me?". He defeated Akkiyalvan by proving through the accepted rules of logic that Akkiyalvan's mother was barren, the king was not righteous and the queen unchaste. The king and queen, impressed that the boy has understood the shortcomings of logic, adopted him.The queen hailed the boy as "Alavandhaar"- the saviour. In other versions of the legend, he is given half the kingdom. There is no historical record to show his reign so it is possible that this happened in a smaller village rather than the kingdom of Pandya.
After years of rule, Mannakal Nambi tricked him into visiting the temple of Ranganatha. There, he had an epiphany and gave up the material duties of a king and became a sanyasin embracing saranagati. He composed the chatushloki and Strotra Ratna at that spot. Mannakal Nambi handed over the reins of Natha Muni's school including the collected Divya Prabandha and renamed him Yamuna Muni or Yamunacharya.
After the demise of Alavandar, Srirangam was led by the latter's son Thiruvarangan, however the place lacked the divine touch. According to a legend, Lord Ranganatha himself instructed Mahapurna to go to Kanchi and invite Ramanuja to Srirangam.
Alavandar, like Ramanuja, focused both on philosophical debates like dvaita vs. advaita and bhakti prayers and the works attributed to him are in Sanskrit although he codified the heritage of the Tamil Alvars. Works attributed to him are: