 The Torelli family ruled Guastalla until 1539, when it was purchased by Ferrante Gonzaga.Another branch of the Torelli family held the County of Montechiarugolo, which was created in 1456 from a split in the County of Guastalla, until 1612.Ferrante Gonzaga's descendants ruled Guastalla until 1746, being raised to the title of duke in 1621, when the territory became the Duchy of Guastalla.