DNA does get around. For example a black tribe in South Africa was discovered to be from the Hebrew priestly tribe in Yemen; Macedonian Greeks and later Romans likely lived, and their descent might still live in China; DNA and art associated with ancient Japan has been found in a single Indian tribe in New Mexico, but not in any others; and an extinct Indian tribe in southern Florida has connections to tribes in South America, but nowhere in between.
Pretty good book.
The Zuni Enigma : A Native American People's Possible Japanese Connection