[gleeaikin]

I remember reading that some early US explorers of the West who were Welsh ancestry said they could communicate with the Mandan using Welsh.

[SunkenCiv]

https://www.freerepublic.com/focus/chat/2155638/posts?page=14#14

[blam]

"I remember reading that some early US explorers of the West who were Welsh ancestry said they could communicate with the Mandan using Welsh."

I've read that president Thomas Jefferson told the Lewis & Clark Expedition not to come back with claims of light skinned people who 'understood' Welsh words. He was already fearful that other countries would lay claim to the western areas and that issue could complicate things.

"President Thomas Jefferson commissioned the expedition shortly after the Louisiana Purchase in 1803 to explore and to map the newly acquired territory, to find a practical route across the western half of the continent, and to establish an American presence in this territory before European powers attempted to establish claims in the region."

[Vigilanteman]

Mandan is of the Sioux language family. Supposedly, it has some vocabulary similar to Welsh. The earliest forms of a Siouxian written language is the winter count which uses symbols similar to Chinese characters (kanji).

It may be purely coincidental, but there are other explanations as well.

If you care to explore that rabbit hole, you can put "Welsh Indians" into your search engine.