Evidence suggests that Heru'ur brought the Tagrean ancestors from Earth, enslaved them, and abandoned them many years ago when the resources were depleted. In an act of defiance against a false god, the Tagreans destroyed all historical records and buried the stargate, which they called the "Ring of the Gods," under a coverstone inscribed with the words, "Here lies the chaapa'ai of Heru'ur, false god to the people of Tagrea. May it never know the daylight again."
With no archaeological data, no ancient writings, and no documentation, Tagrea is a planet without a history. Only in the last 300 years have historical records been kept again. A small group of Tagreans continue to worship Heru'ur, also known as Horus, in secret, believing him to be the creator of all life who spoke them into existence, but to the majority of the population, the Ring of the Gods is a myth and past history has no intrinsic value to the New Era.
SG-1 encountered the Tagreans when the Prometheus became stranded in space after a malfunction of the hyperdrive. Chairman Ashwan, the political leader, welcomed them as honored guests whereas Commander Kalfas, the military leader, greeted them with suspicion and mistrust. SG-1 was able to unearth the Tagrean stargate to return home, and the two worlds opened diplomatic relations.
Episode Reference: Memento