The fair-haired tribal people of Omega IV, long at war with the Kohms, whose sacred words turn out to be a garbled form of the American Constitution in The Omega Glory.
The Yangs are one of the two peoples of Omega IV, seen in the original series episode The Omega Glory. After a devastating bacteriological war in the distant past they were driven from their lands by the Kohms and reduced to a nomadic, warrior existence, although like all Omegans they enjoy lifespans of many centuries.
In 2268 Captain Ronald Tracey of the USS Exeter breaks the Prime Directive by using phasers to help the Kohms slaughter Yang warriors. Kirk, Spock and McCoy are imprisoned with the Yang chief Cloud William and his mate.
Kirk realises that Yangs and Kohms echo Yankees and Communists, and that the Yang holy words are a corrupted version of the United States Constitution. He reads the document aloud and urges the Yangs to apply its freedoms to everyone, Kohms included.