The Zuni tribe have perplexed anthropologists with their language. They speak a language that is too similar to Japanese to be coincidental. Anthropologists can't figure out why this would be the case.
Some similar words as an example. Clan in Zuni is 'kwe,' in Japanese 'kwai.' The word for priest is 'shawani' in Japanese and 'shiwani' in Zuni. Both Zuni and Japanese use the verb as the last word of a sentence, a feature only 45% of languages share. This might not seem like much, but the Zuni language is very different in this than other languages around them.
This sparked some research and scientist discovered that both Zuni and the Japanese have similar frequency of Type B blood, a rare kind of kidney disease and very specific oral traditions about their origins. The working theory is that Buddhist missionaries somehow made it to California around the 12th century somehow.