Amachadi Thevan, a member of the untouchable Pulaya community, was born on Perumbalam Island in Cherthala Taluk, Alappuzha district. Despite the obstacles he faced due to his lower caste, he was fortunate enough to receive primary education thanks to the help of a revolutionary woman named Achukutty Amma. However, he was expelled from his foster house due to protests from high-caste people and was forced to become a bonded worker in the paddy fields like other Pulayas.
Despite his circumstances, Thevan was able to read the works of social reformers and became interested in the writings of Mahatma Gandhi and Sree Narayana Guru. During this time, he was falsely accused by a high-caste gang and brutally tortured by the police. However, he remained steadfast in his opposition to untouchability and became a strong supporter of the Congress party. He even began to wear white clothing, which was unacceptable to the upper castes.
When the Congress party called for a mass struggle against untouchability and unapproachability, T. K. Madhavan met with Thevan as part of his efforts to start the Vaikom Satyagraha. During the Satyagraha, Thevan and a group of low-caste Pulayas entered the Poothotta temple and prayed before the deity, leading to their arrest and two-week imprisonment. Despite this, Thevan remained a strong Congressman and participated in the Vaikkom Satyagraha with the support of K. P. Keshava Menon and T. K. Madhavan.
During the Satyagraha, Thevan was attacked by goons of high-caste Namboodiris, and lime solution was poured into his eyes, nearly blinding him. After hearing about the incident from K.P. Keshava Menon, Mahatma Gandhi sent medicines that helped Thevan regain his eyesight. Despite being arrested and tortured by the police during the Vaikom Satyagraha, Thevan returned from jail in 1925 to find that his dwelling in Amachadi had been destroyed by high-caste people. However, with the help of T. K. Madhavan, he was able to secure one acre of land on the island where he lived as a Congressman until his death.
A memorial has been erected in Amachadi Thuruth in memory of Thevan, but it is in a ruined condition.