Thirumoolar was originally a yogi called Sundarar, residing in Mount Kailash area of Himalayas. Once he decided to undertake a journey to see a friend and fellow yogi. This friend resided in the Potheya Mountains of south India. He was known as Yogi Agasthiyar. Nearing the end of his journey, near the village called Saathanoore he saw a sight that deeply moved him. He noticed a herd of cows lowing miserably around the dead body of their cowherd, Mulan. This yogi Thirumoolar who knew well "Anbe Sivam" (God is Love), felt he should do something to alleviate the suffering of these poor creatures. Through the use of his yogic powers, he put his body in a hollow log for safe keeping and then left it to enter the body of the dead Mulan. The cows were overjoyed to see their master returning to them. He then led them back to the village. After leaving them safely at home, he returned to the old log where he had left his body. He was shocked to find that his body had disappeared. This yogi remained in the cowherd's body and became famous for the verses he uttered when he occasionally would come out of Samadhi (contemplative absorption). In this fashion, 3000 verses were recorded, and these are now known as THIRUMANDIRAM. (Thiru means Holy and Mandiram means the glorious words)

According to Thirumandiram the seminal text of Saiva Siddhanta thirumoolar was born In the Tamil month of purratathi. It is believed that he lived for 3000 years and 13 days. He attained Samadhi in Chidambaram a place in south India. Thirumandiram has 9 tantras (chapters).In the Third tantra verses 549-631 describe the ways Ashtanga Yoga may be practiced, and verses 632-639 highlight the rewards of Ashtanga Yoga practice. Similarly verses 640-740 describe the eight Siddhis (paths of enlighment) and how they may be pursued. The sadhakas state in Samadhi or the attainment of immortality through Samadhi yoga and the other similar achievements of yogic discipline are all described in great deal. Even sexual practices in pariyanga yoga are referenced here, and far more frankly than in works of sage patanjali.such is the influence of Sage thirumoolar and his Thirumandiram.