I also managed to find a couple of articles about the quest for Martin, the appaloosa horse seen in Kyrgyzstan.
Birmingham TV presenter reveals all about his quest for a rare horse.
How did the Appaloosa horse get to North America?
The tl;dr summary goes as follows:
Completely by chance, Scott Engstrom happened to watch a previous TV programme made by Conor Woodman in which he went around the world trying his hand at trading things. She saw him trying to sell horses in Kyrgyzstan and spotted (ha ha!) that one of them was an appaloosa. This intrigued her because it supported her theory that the appaloosa had come not from Spain but from Asia.
Scott pestered Woodman via email and eventually persuaded him to return to Kyrgyzstan and help her search for Martin, the horse he had sold. The trail soon went cold as Martin had been sold on several times, but they were then told that herds of these horses still remained in an obscure corner of Kyrgyzstan tucked away between Russia and China and only reachable via high mountain passes. After an epic ride across absolutely stunning landscapes, they did indeed find the appaloosas and took DNA samples which confirmed that the Asian horses are closely related to the ones in the USA.
I loved this quote from the History Extra page:
Conor Woodman: Now, I tell people the film is a great inspirational story. At the time, I was thinking, “Oh my God, I’m going to kill an old lady making a film, this is terrible.” But she was so strong, and she was determined she wasn’t going to let the mountains beat her.
Interviewer: In the wilds, you found horses with Appaloosa-like qualities that DNA tests confirm as related to North American horses. Does this reengineer how we need to think about American history and the people who brought the horses over?
Conor Woodman: That’s a really good question now. [Horse expert and Texas-based geneticist] Dr Cothran’s best guess was that it was probably people coming over from Asia hunting or looking for furs [who brought the horses] – and they could have been pre-Columbus, or they could have been around the same time as Columbus, or they could have been slightly after Columbus, we don’t really know. The other theory is they migrated themselves by land.
As I once owned a spotted pony (see icon), I found all this very intriguing. To confirm Scott's theory beyond doubt, someone would have to find horse remains in the NW USA that pre-date Columbus, but whether that evidence will ever be found, I have no idea. Ancient bones in the UK and Europe are generally found in caves or burials. Are there any such things in that area? Could the evidence have survived?