This essay refers to part of the results of a PhD study dedicated to the correspondence of the Regnum Sardiniae et Corsicae during the reign of Alfonso the Magnanimous which is part of the series of the Cartas Reales of the Archive of the Crown of Aragon. The content of this correspondence informs us primarily about the political and administrative situation of Sardinia. However, through the analysis of this documentation, the “Sardinian-Iberian” territories appear as a vibrant stage on which people, goods and ideas circulated widely. The study of the letters sent by the officer of Sardinia to the Royal Court, will contribute to reconstruct the movements of Vincentello of Istria, count of Corsica in Crown service, and his brother Johan before the siege of Calvi and Bonifacio (1420-1421).