War...war never changes.
Even now some 204 years after the nuclear holocaust that pushed humanity to the fringes of survival, at least those unfortunate enough not to be in a vault. Those in the vaults faced their own problems from the inherent social experiements many vaults were. Those outside the vaults on the other hand, were forsaken by their countries over something as foolish as a lack of gasoline but that proved to be the point of no return starting with skirmishes, escalating to battles and invasions and reaching the breaking point that was later known as The Great War. A two hour nuclear exchange which changed the face of the earth as it once was and led to an almost eternal nuclear desertification.
The people who lived through the war and initial fallout had nothing to look forward to and many believed that hell had finally reached the surface. Many post-fallout survivors turned to the darker, immoral and evil side of life...in the beginning it was rampant. Rape, murder, robbery, torture and slavery became the norm for a time. When those in the vaults received the all clear what they saw shocked and sickened them. All the worst humanity had to offer, all within walking distance of their sanctuary. As such they had to utilize natural and man made defenses. Cities started to be built from the small shanty towns outside the vaults. This of course meant contact with those unscrupulous characters but also saw them seeing the the defeated vestiges of humanity and those who could help, did what they could. Still the ever present danger lurking in the wasteland ammounted to more than just the cruelty and immorality of men. The fallout caused mutations to many normal creatures and animals changing them into huge abominations with some baring no resemblance to their former selves. There are also tales that somewhere in the big empty, many of the feared mutant creatures were genetically engineered by the remnats of some pre-war corporation.
There were many natural dangers and obstacles as well, after humanity started to reform. The Great Divide is a treacherous journey to even the most hardened survivor of the wastes. It has claimed many victims and is a legendary place of destruction and the full wrath of nature. The radiation of the wasteland has also claimed many lives, though some become ghouls, souless shells of over-radiated humans who only think of killing. That is if they're feral, non-feral ghouls are those who managed to keep their humanity in the face of insurrmountable odds. The mountains that were created from the war also provide obstacle to any who looks to travel through the waste quickly on a linear path.
There are a great many legends in the wasteland, the Mojave in fact has some fairly chilling legends and some laughable. The Sierra Madre is a legend in how she was lost to the world, and know is highly sought after by fortune seekers. The Burned Man, formerly the Malpais Legate of Caesar's Legion is rumored to still be alive and Caesar forbids any to speak of him, with the punishment of death. Others though you'll need to discover for yourself...