Wasteland

"The desert was looking deserted and alone. But it was kinda hard to put another one next to it." - Kamagurka The Wasteland or Wastes basically describes the majority of the globe in the Fallout universe. After the bombs fell, the majority of native plant and animal life was destroyed creating a vast, arid emptiness. Along with the ecological damage, all human structures were partially to fully destroyed. When the survivors emerged from their shelter, they saw this desolation and aptly named it "the Wastes". Not all buildings were destroyed, possibly because of their structure, some still stood i.e. The Super Duper Mart or the Arlington Library in Fallout 3 

The wastes are full of baddies such as molerats to deathclaws