Nal Hutta was originally known as Evocar. The native population of Evocii allowed the Hutts to own a small province on their planet. Unfortunately, the Hutts exchanged technology for land, which allowed them to eventually buyout the entire planet from the Evocii. As a result, in 15,000 BBY (Before the Battle of Yavin), when the Hutt homeworld of Varl was destroyed, the Hutts took complete ownership of the planet away from the Evocii.
Under the new ownership, the planets landscape was altered forever. They started strip-mining operations and heavy industrialization, which further polluted the planet causing a constant drizzle of greasy rain. In the end, the Hutts transformed this lush jungle world into a polluted and barren wasteland.
"What a vile world this is."
"The Hutts know it as 'Glorious Jewel'."
- Malik Carr and Nom Anor
Although the Evocii attempted to seek help from the Galactic Republic, their contracts with the Hutts were legally binding. Perhaps as a result, the Evocii were eventually evicted from the planet and forced to relocated to the planet's fifth moon. While there, the Evocii were enslaved to build the cities on Nar Shaddaa. Their labor lasted five centuries and, upon finishing, the Evocii were freed by the Hutts. The Evocii were then cast out into the Nar Shaddaa's undercity and began to mutate into savages.
Nal Hutta and its moon became havens for smugglers, pirates, and other criminals. Nar Shaddaa would rival Coruscant as the hub of interstellar trade. It is for this reason that Nal Hutta could be considered the opposite of Coruscant.
On this dangerous and toxic planet you will attempt to make a name for yourself as a Bounty Hunter. Whether you attempt to help the native population or take advantage of them is up to you. Though one thing is certain, making the wrong people mad on this planet might cause you to end up in a toxic pit. Good luck.