Information taken from FO:NV forums.

' you'll start in Freeside, an area just off the strip. From there, you'll have 20 minutes to explore wherever you like within the Mojave Wasteland or check out nearby locales like the Atomic Wrangler Casino or tangle with a faction aptly known as The Kings. Don't worry... we'll provide plenty of Stimpaks and weapons so you can survive' Bethesda news letter.

J.E. Sawyer: "The Kings are not one of the major factions (when compared to NCR or Caesar's Legion, anyway), but they are most powerful group in Freeside."