medieval and renaissance horse and barding information from Art by Cindy Walker

"Horses in the Middle Ages differed in size, build and breed to the modern horse, and were, on average, smaller. They were also more central to society than their modern counterparts, being essential for war, agriculture, and transport. Consequently, specific types of horses developed, many of which have no modern equivalent. While an understanding of modern horse breeds and equestrianism is vital for any analysis of the medieval horse, researchers also need to consider documentary (both written and pictorial) and archeological evidence.

Horses in the Middle Ages were rarely differentiated by breed, but rather by use. This led them to be described, for example, as "chargers" (war horses), "palfreys" (riding horses), cart horses or packhorses. Reference is also given to their place of origin -such as "Spanish horses," but whether this referred to one breed or several is unknown. Another difficulty arising during any study of medieval documents or literature is the flexibility of the medieval languages, where several words can be used for one thing (or, conversely, several objects are described by one word). Words such as 'courser' and 'charger' are used interchangeably (even within one document), and where one epic may speak disparagingly of a rouncey, another praises its skill and swiftness.

Significant technological advances in equestrian equipment, often introduced from other cultures, allowed for significant changes in both warfare and agriculture. In particular, improved designs for the solid-treed saddle as well as the arrival of the stirrup, horseshoe and horse collar were significant advances in medieval society.

Consequently, the assumptions and theories developed by historians are not definitive, and debate still rages on many issues, such as the breeding or size of the horse, and a number of sources must be consulted in order to understand the breadth of the subject." There is MUCH more info here!

a few good links... I will try to add more as I find them

from Wikipedia "Classical dressage evolved from cavalry movements and training for the battlefield, and has since developed into the competitive dressage seen today. Classical riding is the art of riding in harmony with, rather than against, the horse. Correct classical riding only occurs when the rider has a good seat and a correct and well-balanced body position, moves with the horse's motion, and gives and times the aids correctly."

The Spanish Riding School

from Wikipedia "The Spanish Riding School (de: Spanische Hofreitschule, the "Spanish Court Riding-School") of Vienna, Austria, is a traditional riding school for Lipizzan horses, which perform in the Winter Riding School in the Hofburg. Not only is it a center for classical dressage, the headquarters is a tourist attraction in Vienna that offers public performances as well as permitting public viewing of some training sessions. The presentation builds on four centuries of experience and tradition in classical dressage. The leading horses and riders of the school also periodically tour and perform worldwide.