Lancians are a cultural region based on the religious traditions of a Minor Human Race known as the Kukhunen (Kukhun/Gushemege 3105). Nearly every member of the Kukhunen race is a Lancian, but not all Lancians are Kukhunen. In fact, most Lancians probably
aren't Kukhunen, and I'm pretty sure you don't even have to be a human to be one.
The original concept was developed in an extensive writeup by David Burden in the
Signal-GK fanzine, so I do not know if they have achieved canonicity yet, though I suspect that they will.
Here's an Internet Archive link to the original
Signal-GK issue with the writeup; it should tell you everything you need to know about the Lancians/Kukhunen. The Zhodani Base has
another article by Burden that goes into a little more detail, although note that the bulk of that article is just the original Signal-GK story.
Aside from being slightly taller and thinner than Solomani/Vilani, and for being traditional vegetarians, Kukhunen don't appear to be remarkably different from the bulk of humaniti. Both the Kukhunen and a neighboring non-human race known as the S'mrii were, due to their unfortunate astrographical positions, early conquests of the Vilani, falling under their cultural and political domination almost 4,000 years before the Consolidation Wars even started. The S'mrii were already a starfaring race (sublight) at the time of Vilani contact, and had been for almost 3,000 years; the Kukhunen were at TL-4.
