In the 18th and 19th centuries, during the Spanish Colonial era, the Atimonan was suffering from frequent attacks by Pirates and outlaws.

As they moved further west, they found a huge, serene and attractive flat land area where they later established the town proper.

The Philippine National Railways established a permanent train station which also contributed to the migration of people to this place.

The culmination of this endeavor happened on April 1, 1939, when President Manuel L. Quezon signed Executive Order No.

It consisted of the barrios of Agdangan, Binagbag, Calutan, Dayap, Ibabang Kinagunau, Ilayang Kinagunan, Maligaya, and Sildura, all former parts of the town of Unisan.

Through the years, without any lucrative source of income and industries, the modern-day Agdangan has already improved in terms of infrastructure.

The resilience, diligence, peacefulness and simplicity of people of Agdangan have been the key factors of its success.