In 2350, a group of Native Americans from Earth settled on Dorvan V, having searched for a new home since 2170. The settlers were worried about losing their traditional culture on an increasingly culturally-homogeneous Earth, and this was the main reason for their quest. As a result, in the 24th century, the population still lived much like their ancestors did many centuries before.
The world was part of the Federation until 2370 when it was placed under Cardassian rule by the Federation-Cardassian Treaty. The Federation, worried about the well-being of the settlers under Cardassian jurisdiction, sent the USS Enterprise-D to try to convince them to relocate. However they chose to stay, citing a spiritual bond with the place. (TNG: "Journey's End")