Icelandic horses are unique, and their history is amazing. Here’s a quick summary. In the year 982 (yes, nine eighty-two!) a law was passed in Iceland forbidding any horse from being imported into Iceland. A horse can leave the country, but it can never come back.
https://icelandwithkids.com/2017/08/27/icelandic-horses-how-to-see-them-and-where-to-ride-them/