This lore can be found on Hutta.
When the Hutts resettled on Hutta, they quickly bought up the entire planet and forced the native Evocii offworld. Lacking any reliable means of interstellar travel, the Evocii had no choice but to allow the Hutts to facilitate their relocation to the orbiting moon of Nar Shaddaa. Countless Evocii were herded onto Hutt cruisers, the Hutts cramming as many natives into each ship as possible. The Hutt shipping containers were not designed to transport living cargo, however, causing thousands of Evocii deaths during the voyage. Worst of all, Nar Shaddaa proved to only be a temporary refuge for the Evocii, as the Hutts already had plans to annex the moon and use the Evocii as cheap labor.