In the 14th century, the Rossi family established a notable presence in the region, including Berceto and Terenzo, located at the foot of the Parma Apennines, within the episcopal patrimony.

He held this position until he died in 1377,[Notes 1] overseeing the mense and revenues from territories such as Berceto, Bardone, Corniglio, Bosco, Roccaprebalza, Roccaferrara, Corniana, and Castrignano, which became significant holdings for the Rossi family in the following century.

[4] John I sought to expand his influence in northern Italy on behalf of the Guelph faction and occupied a substantial part of Emilia, including Parma, Reggio, and Modena.

[5] According to historian Marco Gentile, the Rossi family were uniquely positioned as the sole holders of the title of Count of Berceto, despite numerous other acquisitions.

[8] In 1346, a significant political shift occurred when Luchino Visconti acquired Parma for 60,000 gold florins from Obizzo III d'Este, the Marquis of Ferrara, who had held the city for two years after taking it from Azzo di Correggio.

[11] The Rossi family's influence extended beyond Parma to surrounding territories, partly due to migration from these areas to the city, which was accelerated by the demographic impact of the Black Death pandemic of 1348.

The Sanvitale, Correggio, and Pallavicino families held seats on Parma's councils and occupied significant positions within the local administration, which afforded them influence over the city's political affairs.

[22] Bertrando continued the production of works initiated by his relative Ugolino, including the Pontificale, intended for episcopal use, and the Messale, which serves as an obituary and records the birth of Pietro Maria.

In 1397, Giovanni and his brother Pietro occupied the castle of Scipione in Salsomaggiore Terme, which the Rossis claimed under a contested will that was ultimately deemed invalid.

Despite this setback, Pietro Rossi and Ottobon formed a strategic alliance in 1404 to maintain control of Parma, despite opposition from Giovanni Maria Visconti, who subsequently appealed to the Apennine Guelphs for support.

Initially, their plan was successful, but Ottobon soon removed Pietro from his position, leading to a prolonged conflict that caused significant damage to the Parma region.

[25] In their bid to control half of Pontremoli, the Rossi family pledged allegiance to King Charles VI of France, who was also the ruler of Genoa, to secure his support.

During this time, Giacomo Rossi, who had been the Bishop of Verona, left the city due to its invasion by the Venetians and took responsibility for the Diocese of Luni (Dioecesis Lunensis).

In 1408, the Rossi family joined an alliance led by Niccolò III d'Este against Ottobon Terzi and presented the Marquis of Ferrara with a 24-chapter document detailing their grievances.

[28] In 1409, the Rossi approached the Venetians to offer their services against the Freschi, who supported Jean II Le Maingre, the governor of Genoa on behalf of Charles VI of France.

As a result, the Rossi family regained a significant portion of their claims, establishing a cohesive geographical area consisting of eight towns and numerous castles, with Felino at its center.