Florence is during 1400 and 1500 at the peak of its success. It is the most important, beautiful and incredible city of the world because it concentrates within its walls many great minds, perhaps the most brilliant of the time.

You could say it seems that all the Great people of the time was born in Florence, or has  moved there in order to breathe that magic air. To think of Florence as the cradle of painting, sculpture and architecture is, however, profoundly wrong and limiting because Florence was mothered much more. Modern science, for example, the one based on experimentation, was born in Florence with Galileo Galilei, who, although born in Pisa, grows up and works in Florence under the patronage of the Medici.
Also the opera is Florentine.
Until almost the end of 1500 there was the madrigal: a mix of dance, poetry, drama and songs that usually was represented in private homes.
In 1589 on the occasion of the marriage of Ferdinand II Medici to Vittoria della Rovere something new is represented on the scene: "The Pilgrim".  A work partly sung and partly played with only occasional moments dedicated to the orchestra.
Immediately after, in 1590, the Camerata dei Bardi was founded. It was formed  by a group of friends including musicians and poets, among them Vincenzo Galilei (father of Galileo), Giulio Caccini and Piero Strozzi. Their purpose was to revive classic Greek tragedy with music and to develop a new tuning  that favoured the sweetness of the instrument’s sound rather than the adherence to strict numerical relationships between notes that was taught and followed at the time.
Jacopo Peri, inspired by their work, composed in 1594 "Daphne" (whose text and music got lost) and in 1600, in collaboration with Caccini – text - and Rinuccini – music-, "Euridice" to celebrate the wedding of Maria de Medici to the King of France, Henry IV.
Thus the first opera was born in 1600 and performed in Florence in the Palazzo Pitti, Medici palace.

So it is not a chance that all music is written in Italian or better said, in the vernacular of Florence.