The mother town of Sison is San Fabian. Bulaoan, formerly a big barrio of San Fabian became a municipality named Alava in 1868. In 1907, the township of Esperanza was organized. That same year, the township of Labayug was also organized. Later, these two townships (Esperanza and Labayug) fused together to form the township of Artacho. The town of Alava had been making moves to expand its jurisdiction. Likewise, the township of Artacho had also a move to become a regular municipality. As a result of their efforts, they fused as one. The fusion was sponsored by the late Senator Pedro Ma. Sison in the Senate. On May 1, 1918, the fusion was made and the town was named Sison, after its sponsor, Senator Sison.