An allasomorph was an anthropomorphic shapeshifting species, once thought to be only rumor, capable of altering its molecular structure into that of other species. The species was mentioned in the galactic zoological catalog. Their homeworld was Daled IV and its moons. (TNG: "The Dauphin")
In the mid-2360s, there was no formal contact between Daled IV and the United Federation of Planets. As such, little information was known to them during this time. However, the planet was tidally locked, resulting in very different cultures between the two hemispheres. The two sides were frequently in conflict throughout their recorded history.
In 2349, a man from one side and a woman from the other had a child, Salia, hoping that her not being from either side would one day allow her to neutrally govern and unify the planet. They contacted the Federation, and asked for a Starfleet ship to transport her to Klavdia III, where she was to train for sixteen years before her return. The parents died shortly thereafter, killed during the conflict.
In 2365, Starfleet sent the USS Enterprise-D to Klavdia III to pick up Salia, and transport her (and her caretaker Anya) back to Daled IV. Although Salia was slightly reluctant to govern her people, having been isolated for so long, she did decide to beam down and take her place in the government. Salia wished that her world would one day have formal contact with the Federation. (TNG: "The Dauphin")