The 8th Dimension Description

The Alteriia, after expanding to the 5th Dimension, knew they would need access to more raw materials.
With their food and science bases up, they had to find a dimension near-by that would allow them to build up thier military in the event of war.

The 8th Dimension was perfect.
Laden through and through with the ultra-valuable Star-Iron, which can be smelted into Star-Steel when combined with Rock Lily, imported from Lady Zyria's lands, the 8th dimension seemed the next logical expansion point, despite that the 7th was closer, as the 7th had significantly less resources, and was already partially occupied by the Plutonians.

The 8th Dimension was however, home to a native species known as the "Yisilyec" (Or, the Sky People)
The Yisilyec, while having strong minds and bodies (which possessed the ability to fly, due to wing like structures along the spine, and along the bone systems on the front of their bodies) were not yet to the technological advancement level as the Alteriia were.
The Alteriia, bound by their own honor, did not want to fight the Yisilyec, so the politely began trading with them, hoping to increase relations until the Yisilyec would want to form an alliance with the Alteriia.

Before relations could develope very far however, the Yisilyec found themselves under attack from a far superior technologically race from the higher dimensions.
The Alteriia, bound by honor, and the wishes to protect their investment, quickly intervened and destroyed the cruel invaders. In thankfulness, the Yisilyec agreed to combine the two species together in the Ragla Krios. "The Feather Pact" For centuries now, the Yisilyec and the Alteriia have been indistinguishable allies, and are indeed, a part of the same galactic empire. They both benefit from the relationship.

The 8th dimension is home to much of the mining and other resource gathering of the Alteriia, as well as the main provinces of weapons and military production.
It is also home to a large portion of the Standing Alteriia Military, and is also a popular vacation destination, due to the mystic, "Veil of Stars" which is a natural phenomenon occurring three times a year on the Yisilyec's planet.