A brief history of classical dressage....from Wikipedia!
In the 15th century, brute force training largely came to an end while artistry in riding was once again coming into its own.
Along with these developments came indoor riding. The Renaissance gives rise to a new and enlightened approach to riding as a part of the general cultivation of the arts. By the Victorian age indoor riding had become a sophisticated art, with both rider and horse spending many years perfecting their form.
Gueriniere, Eisenberg, Andrade and Marialva write treatises on technique and theory.
The horses were trained for a number of airs or schools, above the ground movements that enabled their riders to escape if surrounded, or to fight more easily. These included movements such as levade, capriole, courbette, ballotade. Movements still seen today in dressage include the piaffe, passage, and half-pass.