Beta III was the Archon's last destination; the ship was forced down and destroyed there by Landru in 2167. According to Reger, though the Archons attempted to resist Landru, many were killed in this endeavor, while others were ultimately absorbed into the Body.
When the scouting party from the USS Enterprise, consisting of Lieutenants Sulu and O'Neil, visited the planet in 2267, they were soon identified by the Lawgivers as being Archons because the clothes they were wearing were incorrect.
A second landing party, consisting of Kirk, McCoy, Spock and Lindstrom, returned to the planet, this time wearing proper attire, a native named Reger and Tamar became suspicious, ultimately questioning if they too were Archons. When Kirk teased that they might be, both natives, who were from an underground group that was not of the Body, revealed that "It was said more would follow."
Some time later, when a third member of the underground was found, so named Marplon, he also revealed to Spock that "We have been awaiting your return." Though Spock assured him they were not Archons, Marplon did not care, stating, "Whatever you may call yourselves, you are in fulfillment of prophecy. We ask your help."
When Landru himself, or his computer alter ego, was directly confronted by Kirk, Kirk felt it was necessary to reveal that they were indeed the Archons, and expressing his desire to speak to Landru, Landru replied, "Despite my efforts to save you, you have invaded the Body and you are causing great harm." (TOS: "The Return of the Archons")