Nabu was a Human that lived on the planet Polrusso in the Pegasus galaxy. He was one of the first of his people that began to develop enhanced mental powers as part of an experiment by the Ancients on the world. When he was a young man, his village would be attacked by the Wraith that began their culling which abducted his family. In anger, Nabu would focus his telepathic powers on the pilot of the Wraith Dart and caused it to crash. It was only then he realized the scope of what he had done as his family were in the crafts culling generator and were thus killed in the attack.
Despite showing some resistance against the Wraith, the fellow villagers would be frightened of the boy who glowed with light during the use of his powers in the culling. They would shun him and cast him out of their village. Denied any shelter against the approaching sandstorm, Nabu would have died if he had not used his powers to summon a Wraith dart to rescue him. Though it was not his intention, the pilot was already killed and Nabu managed to escape into an abandoned village where he made his home and shelter from the planet's dangerous sandstorms.
By the time he was an adult, Nabu had a frightening appearance with near pale white skin and was often mistaken for a Wraith by the inhabitants. This was not helped by the fact that he would use Wraith Darts to travel around the planet and would save children abandoned by their parents in the sandstorms. These children were exiled due to their deformed appearances or their uncontrollable mental abilities. He would manage to save thousands of children and ensure their development with a viable community. He would also learn much about the 'Ancestors' and their experiments on the world as well as its terraforming which he learnt by gaining access to the Ancient terraforming facilities. (SGA: "Exogenesis")