The Diocese of Tortosa gives a certain foundation to an ancient historical region that, despite having no political representation, shares common historical, cultural and linguistic ties. This territory is known as Ilercavonia in academic and scientific circles.[4]
Following the De mutatione finium Dioecesium Valentinae-Segorbicensis-Dertotensis decree, of 31 May 1960, the parishes of Nules, Vila-real, Castelló de la Plana, Lucena and Albocàsser that had historically belonged to the Diocese of Tortosa were aggregated to the Diocese of Segorbe-Castellón along with the parish of Betxí. Francoist propaganda presented the changes as an occasion for rejoicing.