Anthwara brought his people to the planet because he believed that the trees and wind and the rest of nature welcomed them. They had been there for twenty years when the Federation ceded the planet to the Cardassians in the treaty of 2370. Anthwara refused to remove his people from the planet. Captain Jean-Luc Picard told him that no was not acceptable. Anthwara said that Picard would not remove his people from that planet, because Picard was here to protect the Native Americans to atone for the sins of his ancestor Javier Maribona-Picard who had taken part in the Pueblo Revolt in 1680.
Hostilities nearly broke out between Picard, obliged to defend the Federation citizens, and Gul Evek, determined to claim the planet as stipulated by the treaty, but Picard was able to convince Evek to stand down. Anthwara was able to convince both sides to let his people stay under Cardassian rule and forgo Federation citizenship. He told Picard that he had atoned for his ancestors' blood stain against the Native Americans. (TNG: "Journey's End")