They evolved from a small, multi-toed ancestor called Eohippus about 55 million years ago. Over millions of years, horses gradually evolved into the single-toed, larger animals we know today.
However, horses became extinct in North America around 10,000 years ago, likely due to climate change and the arrival of humans. They were reintroduced to the Americas by European colonists in the 15th and 16th centuries.
So, while horses are originally from North America, they were reintroduced to the continent after being extinct for a long period.