Yang

The Yangs were the Yankees of Omega IV. They were engaged for many years in conflict with the Kohms. The Yangs held an American flag and a copy of the American Constitution as sacred items and words handed down by God. When James T. Kirk corrected their 'sacred words' they seamed unaware that any other culture knew American history. (TOS episode: "The Omega Glory")

It was unknown if the Yangs were from 20th century earth, or had evolved in the exact same way as Humans.