Mechanically-speaking, Nagaji in Pathfinder: Domain are identical to those found in the Pathfinder Advanced Race Guide p196. You can also find Racial Information on them on the d20pfSRD website.
XP Cost: 7,000
Tulun Nagaji: Artificially created during the Mythic Era to be footsoldiers for the Naga in their war against the Dracen, when their masters were defeated and forced beneath the waves, the Nagaji were unable to follow and were marooned on the surface of Omisishiru. Knowing nothing else many fought against the Dracen who had superior numbers and training, and many were slain despite their prowess and desperate situation. Eventually however, the Nagaji as a whole were forced to accept they were defeated and surrendered to the Dracen who, impressed with their bravery, loyalty and persistence, actually accepted them into the Empire. The Nagaji have been Imperial Citizens ever since.
Place of Origin: Most Nagaji have only known the lands of Omishiru and many do not seek to travel beyond its borders. Some long to follow their Naga masters whom they still share an undefinable connection with, and some become adventurers who wish to see what the rest of the world has to offer. Though now able to reproduce with their own kind, it is still a rare thing for a Nagaji to be born outside of the borders of the Eastern Kingdom however.