Isn't it crazy that horses have been around 45-55 million years and they used to be multi-toed instead of having one single hoof!
WHAT? NO WAY! I did not know that!  
Yeah pretty nuts! Humans only started domesticating them too around 4000BC
In any part of the world specifically?
That I'm actually not too sure of, but I would assume Mesopotamia because that's where most humans were around that time I think. So modern day Iraq maybe? Correct me if I'm wrong
Ok, and are there different breeds of horses?  
There are hundreds! They divide horses into three different categories. Hot bloods, cold bloods, and warmbloods. 
Wow, and what about racing horses?
," such as draft horses and some ponies, suitable for slow, heavy work; and "warmbloods," developed from crosses between hot bloods and cold bloods, often focusing on creating breeds for specific riding purposes, particularly in Europe. 
Horse breeds are groups of horses with distinctive characteristics that are transmitted consistently to their offspring, such as conformation, color, performance ability, or disposition. These inherited traits are usually the result of a combination of natural crosses and artificial selection methods aimed at producing horses for specific tasks
Horse
The horse ("Equus ferus caballus") is one of two extant subspecies of "Equus ferus". It is an odd-toed ungulate mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature, "Eohippus", into the large, single-toed animal of today. Humans began domesticating horses around 4000 BC, and their domestication is believed to have been widespread by 3000 BC. Horses in the subspecies "