Calbayog's early history has been associated with the introduction and spread of Catholicism in the country. Calbayog started as one of the small settlements on the Island of Samar, an area assigned to the Jesuit missionaries. Jesuit chroniclers, as early as the 17th century, notably Fr. Ignacio Alcina, wrote many accounts about it and its people. Jesuit records and reports referred to the settlement initially as Ibatan and Jibatang (Hibatang). In the annual report of 1739 the name Calbayog appeared for the first time. Fr. de Huerta, a 19th-century Franciscan writer, noted in his work "Estado Geografico" that in earlier times, Calbayog was called Tiayban for having been founded near a river of the same name. Then it was transferred due to a flood to the shore of the Hibatang River, whose name it took. Then again the settlers transferred to the place that they permanently occupied and took the name Calbayog.