It would be easy to gloss shulsagas as the Astral Plane’s githyanki, and their skinny-and-a-bit-too-similarly-craggy-faced art in Bestiary 4 doesn’t help. Don’t give in to that reading though, because first of all, they’ve got a hell of a lot of Silver Surfer in there as well, and there’s more going on besides.
As a “basic” D&D player, I missed the good years of githyanki (and githzerai) mythologizing—mostly during 1e after the Fiend Folio came out (plus I’m assuming plenty of Planescape material), but thanks to Dragon/Dungeon’s Incursion mini-campaign, I know enough to get buy. Unlike githyanki, shulsagas aren’t conquerors…in fact, their violent reputation is due to pure xenophobia and a desire for isolation. Of course, when you're in a transitive plane like the Astral—and worse yet, one with so little useable real estate—interruptions and incursions from other planes are almost a given. So shulsagas are almost doomed to come into conflict with others—especially arrogant and/or meddling adventurers—right from the start.
Also, I find it fascinating that shulsaga tend toward careers as rangers and summoners. This fits their self-sufficient hunter-gatherer lifestyle—hunt what you need and call only the allies you require—but it also poses a certain irony: the isolationist shulsagas prefer the two classes where companions are not only common, but essentially price-of-entry!
And can we take a moment to acknowledge how cool it is that shulsagas astrally skateboard on floating disks and use astral friggin’ leviathans as guard dogs and tugboats?!? Hell yeah, we can. And they pick their own gender at age 100! And they can cook amazing astral leviathan egg frittatas! (Okay, I made that last one up.)
A shulsaga is reaching its centennial—a process that has actually taken more than double that time and many sojourns across the planes (time does not pass in the Astral, after all)—and yearns for the day it can be a full-fledged male. But its settlement is desperate to rebuild its population after daemon attacks, and the settlement’s leader, the Keirmarch, is demanding every potential female do her part. When the shulsaga comes across travelers stranded in the Astral, it agrees to help them if they promise to bring it with them—and if and only if they can fend off its family’s hunting party without using lethal force.
Shulsaga summoners typically call their servitors from the realms of eidolons and other spirit beings. But when a shulsaga summoner begins harvesting servitors from the Demiplane of Dreams—specifically images in an adventurer’s dreams—the adventurer finds himself wracked by pain and haunting visions.
There are tales among the astral leviathan-taming shulsagas that their kind once dined with dragons and danced in their courts on the Infinite Aerie. This is doubtless a fabrication, of course, their sages scoff. Then whole warbands start winding up floating dead in the Astral, their leviathans gutted and the very land shards upon which they lived dragged who knows where. And then come the sightings—red-scaled shulsagas on fiendish cloud and crystal dragons, like the stories of old but far, far worse…
—Pathfinder Bestiary 4 245
Shulsaga was apparently an astral goddess in Sumerian mythology, but that’s the sum total a quick Googling will allow me to find.
The shulsaga from B4 almost got stated up as a new player race, being sort of githyanki like and living on the Astral Plane, but we went a different direction with them—in part after their art didn’t scream “Play Me!”
You’ll notice Wes and I disagree on the past tense of the verb “to stat.” I’ll let you decide who’s right, the professional editor or the blogger with annoying opinions.
(I have a feeling I’m going to pay for that last paragraph...)