Toxic planet

Lost Tribe Homeworld, The Toxic Planet
The Toxic Planet, as it is currently called, is the safe refuge for the Lost Tribe Asgard. Following the Lost Tribe's defeat and destruction of their Intergalactic ships in the battle with the Wraith, the rest of the Asgard abandoned their settlements and made their way to the Toxic World as they could hid from the Wraith were their foe could not follow and finish the pursuit.

For the next 10,000 years the Lost tribe were able to live on this world wearing only simple breathing apparatus and likely rebuilt their technology in that time period in order to adapt in their new surroundings, likely their Ships and Armor were invented in this time frame. The planet likely possessed moderate levels of resources, enough to build interstellar spacecraft, but not enough to reconstruct any vessels like the Bilskirnir-class ship of the main Asgard brethren.

Though over time the atmosphere of the planet became steadily worst, the Lost Tribe in return replaced the now ineffective breathing apparatuses with their Battle Armors, though even this measure failed to completely resolve the problem. As a result, the Lost Tribe were forced to venture for the first time in 10,000 years, into a Wraith dominated galaxy. During their travels they came across the Attero Device, learned about, and eventually got it activated with the aid of Doctors McKay and Jackson though unfortunately for the Lost Tribe the device was destroyed.

It is unlikely the planet possesses a Stargate (or one unburied) as the Lost Tribe only uses their ships for travel, and although their attempt destruction of the Wraith failed, they probably managed to remove a number away from the Toxic Planet during that time. Though, they most likely never manage to relocate enough of their population in time and likely a significant number still remain behind.