Outlanders, in this case people and beings from other worlds, are rare in the Sea of Stars, the Empress has constructed wards and barriers to keep out beings from outside, primarily from the higher and lower planes, but this effects dimensional and world travelers as well. Which the Empress considers a benefit, such people are likely to be destabilizing elements on the world she rules and there are enough of those already.
However, as knowledge of her existence has leaked in garbled form into other worlds, due to no effort of her own, where she is sometime viewed as a savoir of oppressed dragonkin such as kobolds. She will occasionally pluck such beings across the barrier and bring them to the Sea of Stars where they may start a new life. Using such powerful magic has unexpected side efforts however, with other things being dragged in the wake of the chosen beings or odd magical energies being released.
The barrier is designed to keep beings out and it is easy to pass through when leaving the Sea of Stars should someone master the magics involved to do so. The Empress has no problem with people leaving her realm as long as they do not steal from it, that might invite retribution, but any mortal from the Sea of Stars who leave are indelibly marked in their aura and the Empress will know if they return. A large number of people fleeing her realm would also attract her attention which is likely not what such people would want.
Notes: The idea of kobolds being “saved” by the Empress and other people getting dragged through into the wake, I used as a framing mechanism for a introductory D&D I have been GMing.
Image “Kleine Welten VI (Small Worlds VI)” by Vasily Kandinsky (French (born Russia), Moscow 1866–1944 Neuilly-sur-Seine) via The Metropolitan Museum of Art is licensed under CC0 1.0
Sea of Stars RPG Design Journal 