Great Ring of Avidan
From The Stargate Omnipedia
Term the Tegalans called the Stargate, before their learned of its more common name. The Great Ring was discovered in the Corillian wastelands on Rand, and became a centerpiece of the planet's societies.
The Great Ring eventually became so significant that it was responsible for plunging the countries into a devastating war which almost wiped out all of Tegalus's inhabitants.
KEY EPISODE
Icon - SG-1's arrival through the Great Ring of Avidan forces all of a planet to reassess its belief system (and dealings with their neighbors), for the worse.