that is how the horse , by navigational accident , had come home again to america ( that is , if you ignore the icelandic horses arrival nearly 500 years earlier , and overlook a certain transaction made between the norse settlers and a chief of the dogless dorset eskimos , a deal that took place before the relationship between the viking homesteaders and a few milk-drunk skraelings had soured into lactose-intolerant bloodshed ) .