The legend of 'Parayi petta panthirukulam' is centered on Trithala. According to this legend, a Brahmin named Vararuchi, married a lower caste woman named Panchami. After the marriage, they set out on a long journey.[9] During the course of the journey, the Panchami became pregnant several times, and every time she delivered a baby, the husband asked her to leave it there itself.
Each of the babies was taken up by people of different castes (totally 12), thus they grew up in that caste, making the legendary 'Panthirukulam'. They all became famous in their lives and many tales are attributed to them. The eldest was Brahmadathan Agnihothri, a Brahmin, whose place is Mezhathur in Trithala. The others are Pakkanar (Basket weaver), Rajaka (Laundry man), Karakkal Matha (The only female member), Akavur Chathan, Vaduthala Nair (Kshatriya/Warrior), Thiruvalluvar (Philosopher), Uppukuttan (a Muslim), Pananar (a Panar), (Perumthachan (Master carpenter), Naranathu Bhranthan (an eccentric but divine person), Vayillakunnilappan (a child without mouth, whom the mother wanted to keep with her).
Their stories are mentioned in the well known book 'Eithihyamala' by Kottarathil Sankunni.
According to legend, a boy from Vemancheri Mana named Agnihotri (first son of Vararuchi and Panchami) went to the river to bath with his mother. The boy took the sand and made a heap on the shore. When the mother tried to remove it, she found that it was hardened in the form of a Shiva linga. Thus, the famous Trithala siva temple that exists today was built. It is said that the river is said to have the altered course to make the sanctum sanatorium of the temple.
It is mentioned about the temple and temple village in the chapter titled 'Pantheerukulam (Malayalam: പന്തിരുകുലം)', of Aythihyamala written by Kottarathil Shankunni.