Thora

Thora is one of the more recently colonised planets within Federation Space. While evidence of previous habitation on the planet exists, nobody within the current generation knows about any colony that was sent to this planet before the current one

Pre-Colonisation
Evidence from several ruins on the planet's surface appear to suggest that Thoas was colonised by a civilization that likely predates the founding of the Galactic Federation. A few scholars have even theorised that the civilisation predates even the Terran Mandate, although this is an unlikely theory.

The Colony of Thoas
Due to the lack of oxygen in the atmosphere, the Federation allowed for the construction and proliferation of a special pretech device that could be used upon the flora of the planet. According to the scientists who developed the device, it caused plant life within a large radius of the device to be able to produce oxygen during their photosynthesis process, instead of their usual byproducts. This allowed for easy life, free from the perils of asphyxiation. At least, that is what everyone thought.

The War Before
While the most pressing danger on Thoas was its lack of a breathable atmosphere, the presence of ruins on the planet was a cause for concern for most involved. These ruins were in a state of destruction that could not have been caused by the simple passage of time. Indeed, craters of significant size were scattered around large clusters of these ruins, which lead researchers to believe that the previous civilisation fought some kind of war, and lost.

The Alien Menace
After a few years of building up the colony, and the founding of Thoas' first spaceport, the people were attacked by a group of some unknown fauna. Too sophisticated to be a mere animal incursion, the colonists treated the attack as some kind of hostile alien threat, and began arming for war. These "aliens" appear sporadically, and use fast-moving hit and run tactics in their attacks. In moments, these "aliens" swoop in, take off with a few people in a group, and leave just as quickly.

No colonist taken by these "aliens" has ever returned.

Popular Thoas Theories
Disclaimer: The following theories are some of the most popular rumors surrounding the planet of Thoas. Tabaxi's Taxies neither confirms nor validates these theories. Tabaxi's Taxis certainly does not endorse any of these theories.
 * The civilisation on Thoas was one that pre-dated even the Terran Mandate, and must have had some amazing technological advances during their time.
 * The reason for the previous civilisation's destruction must have involved some kind of forbidden maltech.
 * The "aliens" are actually the survivors of the previous civilisation's destruction, and have been quietly living on the planet until the Federation showed up.
 * The "aliens" are some kind of pre-sentient species whose evolution has them just about to reach the cusp of sentience.
 * The previous civilisation was actually a former colony of a galaxy-spanning superpower, not unlike the Federation or the Terran Mandate.