For centuries the Heir'tza fought with the other main faction on the planet, the Heir'och. Things came to a head in the 21st century, when the Heir'och fled to a neighboring planet in the star system, which they named Heir'ocha. Despite a period of relative peace between the two factions, interstellar war soon broke out and persisted on and off for nearly a century.
In the late 22nd century, representatives from each faction who sought for a reconciliation between the two factions discovered that once or twice in a generation, a Heiren with telepathic abilities were born. They hypothesized that if a telepath was born to both factions, then a reconciliation could take place. After waiting for three generations a telepath was born to each side, and they planned the reconciliation ceremony to take place in the city of Heir'at on Heir'tzan in 2251, which would respect the ancient Heiren customs. (TOS - My Brother's Keeper novel: Republic)