It was during the reign of Frederick II (or Frederick I of Sicily) between 1198 and 1250, with his patronage of the Sicilian School of poetry, that Sicilian became the first of the Italic idioms to be used as a literary language (Cipolla 2004 p. 141). The influence of the school and the use of Sicilian itself as a poetic language was acknowledged by the two great Tuscan writers of the early Renaissance period, Dante and Petrarch. The influence of the Sicilian language should not be underestimated in the eventual formulation of a lingua franca that was to become modern Italian