The following occurrences transpired in the year 4166 BBY.
The Mon Calamari had already established an interstellar federation, independent of the Galactic Republic's influence, centuries prior to this year. They are credited with inventing the cavitation hyperdrive sometime during this era, which facilitated the colonization of planets like Ruisto, Mantan, and Hinakuu between 4400 and 4200 BBY.
In the year 4166 BBY, scouts from the Republic, while charting the outer reaches of the Perlemian Trade Route, encountered starships belonging to the Mon Calamari near the planet Ruisto.
For thousands of years, interactions between the Republic and the Mon Calamari remained infrequent. Later in the Republic's history, Mon Calamari Space held representation in the Galactic Senate as an Allied Region. During the age of the Galactic Empire, the Mon Calamari bravely resisted Imperial occupation, forcing their withdrawal in an unprecedented act of defiance, and secretly supported the Rebel Alliance. Their shipyards' production of MC80 Star Cruisers played a crucial role in leveling the playing field during the Galactic Civil War. Following the Battle of Endor, Mon Calamari Space became a founding member of the short-lived Alliance of Free Planets. This sector later became a vital part of both the New Republic and the Galactic Federation of Free Alliances.