The formal foundation is dated 1403, during the rule of the House of Visconti in Milan, but its existence is attested at least since 1346 with the name of Team of Canzo (Squadra Cantii).
In 1435, along with eight other pieves and communal teams (Pieves of Oggiono, Missaglia, Garlate, Brivio, part of that of Agliate, and the teams of Nibionno and that of Mauri), formed the Universitas Montis Briantiae, an aggregation of Medieval communes with voice in front of the ducal authority, and in particular in front of the revenue authority.
[1] It consists in the original, historical extent of "Brianza" region, term whose meaning in modern times has been considerably enlarged.
Those are years of great development of commercial and craft activities, flowering of masons, carpenters, smiths of high technical ability, silk-weave masters, artists and printers appreciated in all Europe.
In 1472, Galeazzo Maria Sforza gave to Negronis' family (Antoni and Damian) (known as Missaglias) rights on Curtis Casalensis.