The history of Saint Thirugnana Sambandar embodies the essence of Saivism, emphasising that reaching the lotus feet of Lord Shiva is the ultimate purpose of human life. Initially resistant to marriage, Tirugnana Sambandar reluctantly agreed when his father, Shivapada Hrudayar, chose Poompavai, the daughter of Sivanesan Chettiar, as his bride. However, Poompavai died from a snake bite, but with Lord Shiva's grace, she was restored to life and was accepted by Sambandar as his daughter. Shivapada Hrudayar then selected Mangai Nallal, daughter of Nambiandar Nambi of Nallur, as the bride. The wedding took place at Achalpuram, with Tiruneelanakka Nayanar conducting the rituals. As Sambandar and his bride circled the wedding fire, he prayed to Lord Shiva for marital protection and praised Him with the Kallur Perumanam hymn. Lord Shiva appeared as a divine light, advising Sambandar and the gathered devotees to join Him. Sambandar, losing himself completely in devotion, sang his final hymn, highlighting the glory of the Panchakshara Mantra: Na Ma Shi Va Ya. The saint, along with all present, merged with the divine light. This event is commemorated each year on the Moola Star day in the month of Vaikasi (May-June).
Puranic Significance:
The historical name of this temple site is "Nallur Perumanam," where "Nallur" refers to the village of the bride of Saint Thirugnana Sambandar, and "Perumanam" means "grand wedding" in Tamil. Other historical names include Shivalogam, Thirunallur, Mukthipuram, and Thirumanavai, with the current name being Achalpuram. This temple is one of the 27 under the administration of the Dharmapuram Adheenam.
Legend states that Shivapada Hrudayar, Sambandar’s father, chose Mangai Nallal (Sthothra Poornambigai), the daughter of Nambiandar Nambi from Nallur, as the bride. The wedding took place at this temple, with Thiruneelanakka Nayanar, one of the 63 Nayanmars, conducting the rituals. During the wedding procession, Sambandar prayed to Lord Shiva for marital protection and praised Him with the Kallur Perumanam hymn. Lord Shiva appeared as a huge fire (Agni), inviting Sambandar and the gathered devotees to merge with Him. Enchanted, Sambandar sang his final hymn, "Namachivaya Thiruppathigam," and merged with Shiva Jyoti along with the gathering, attaining salvation. This event is celebrated each year on the Moola Star day in Vaikasi (May-June).
The temple is unique as it is the only one where four Nayanmars—Tirugnanasambandar, Thiruneelanakka Nayanar, Thiruneelakanda Yazhpanar, and Muruga Nayanar—attained Mukthi (salvation). Tiruneelakanda Yazhpanar’s wife, Mathanga Soolaamaniyar, also achieved salvation here. Goddess Parvathy, who gave Vibhuti (sacred ash) prasadam at the wedding, is revered here as Thiruvennetru Umaiyammai, and the temple is named Achalpuram. The name is thought to derive from "Aayal" (Goddess Parvathi) and "Puram" (place) or "Achariya" (learned guru) and "Puram" (place), reflecting the significance of Saint Thirugnanasambandar.
Sages like Vasishta, Kagabujandar, Viswamithra, Parasara, Jamadagni, Durvasa, Brigu, and Manthatha are said to have had Kailash darshan here. Sage Kagabujandar is believed to have travelled by walking on his hands to preserve the sacredness of the land. Lords Vishnu, Brahma, Murugan, Indra, Chandran, Ganga Devi, and King Manthatha of Ayodhya are also believed to have worshipped here.