The Yang were one of two ethnic groups on the planet Omega IV who, centuries ago, fought a terrible bacteriological war against the Kohms. Yangs were culturally parallel to Earth's 20th century "Yankees" of the USA. After the wars the civilization was destroyed and the Yangs were forced out of the cities into the deserts and hills.
The Yangs learned to wear animal skins, adopted stoic mannerisms, and learned how to use the bow and lance. They began living like the Native Americans, and eventually looked like them. The Yangs worshiped such icons as the American flag and the Constitution of the United States, which their past nation had inexplicably developed, along with the English language, in precisely the same forms as did the USA of Earth, though apparently many centuries earlier. The Yangs' holy words and invocations were garbled versions of the United States' Pledge of Allegiance and Constitution. (TOS: "The Omega Glory")