Derian, pl. deriani
‘Derian’ is a very old Cortiian word, and it literally means ‘rider’. In wider use, it’s a generic title for any Cortiian, rather like ‘citizen’ in the Federated Planets Alliance.
The legend goes something like this; back in pre-spaceflight history, all Cortiians fought from horseback. (Depending on how much of a conspiracy theorist you are, you might see connections to the Earth traditions about ‘nightmare’ and any number of the old Celtic legends about a mounted hunt.)
In actual point of fact, reliable rumour and Cortiian archives indicate that that’s a lovely piece of romanticism, and about what a Central Worlds historian would come up with.
The original Cortii were a mercenary troop (making them, incidentally, the longest-operating mercenary force in human space), and they fought from whichever angle gave them the best advantage. If the shock and awe approach was needed, they would probably have sent in a mounted charge. On the other hand, try sneaking into a fortification on horseback.
However, as spaceflight became increasingly part of everyday life, space, ironically, became a luxury. Overpopulation on the Central Worlds planets, before the advent of population-wide contraception (and the First Colonial Fleet) made keeping large animals of any kind expensive. Space on stations was less of a problem in itself, but the volume of clean air required provided its own constraint. Larger spaceships mass more, and mass is what a drive moves…you get the picture.
Horses became a rarity.
After the First Sector War, the human governments decided that putting some brakes on the Cortii would be a good idea, and forbade recruiting, denied Cortiians interstellar citizenship, and otherwise tried all and any methods short of direct confrontation (which had been proven not to work very well).
By this point, the Cortii had a range of footholds across humanoid space. They declared themselves a separate category of humanoid (see genetic adaptation), and managed to argue that into law as a basis for self-governance.
At about this point, the Cortiian Councils began pushing the use of horses again. As a self-governing sub-species with multiple interstellar settlements, they now had the additional cachet of being a taboo topic in polite society. A few highly visible actions including full mounted units set off a rash of artwork, interactive entertainment shows, and educational programming that did a much better job of recruitment than any formal campaign ever would have, and the Cortiian governing body (the Councils) chose ‘derian’ as their appellation of choice.