Centuries earlier, several threatened tribes, including a mixture of Navajo, Mohican, and Delaware Indians, were transplanted from Earth to Amerind by a group known to them as the Wise Ones. These Wise Ones also placed an obelisk on the planet, which possessed an asteroid deflector, used to protect the planet's inhabitants. By the mid-23rd century the obelisk had malfunctioned and the planet was vulnerable to asteroid collisions.
In 2268, the USS Enterprise was on a mission to divert an asteroid, nearly the size of Luna, off of the collision course it was on with Amerind. Although the Enterprise was unable to stop it, they were able to repair the deflector in the obelisk, which was in turn able to deflect the asteroid, and once again protect the planet. (TOS: "The Paradise Syndrome")
In 2268, the USS Enterprise visited the planet Amerind and discovered a civilization of American Indians living there. The Preservers had evidently transplanted a nearly extinct group of these Indians to Amerind. They may have transplanted various flora and fauna as well, for Amerind was richly populated by Earth-native forms. The inhabitants referred to the Preservers as the "Wise Ones." Because asteroid impacts threatened Amerind on a semi-regular basis, the Preservers constructed a deflector in the form of an obelisk and left instructions with the tribal medicine man.
Leonard McCoy and Spock theorized that the Preservers were responsible for the spread of the many humanoids that populate the galaxy (TOS: "The Paradise Syndrome"). But about a century later, Captain Jean-Luc Picard and archaeologist Richard Galen learned that the Preservers were only part of the reason. (TNG: "The Chase")