The surface of the planet I have envisioned is almost entirely desert save for several city-sized "oases," or pockets of water, flora, and fauna that do not exist elsewhere. The temperature fluctuations on this planet are abnormally high, perhaps resembling that of the Gobi Desert in China (around -20 Fahrenheit to 90+ Fahrenheit in one day-night cycle). This would mean that at night, the desert would freeze over, but by midday, temperatures would be sweltering.
Would humans be able to live on such a planet (as a full-on civilization, not just as nomads)? I expect that humans would settle at these "oases" and begin agriculture there, but with such dramatic climate variations, would that even be feasible?
Assume for this question that this civilization has access to Renaissance-level technology, and that this planet's wildlife resembles that of Earth's.
Addendum: Due to the abundance of questions on the topic, I figure I should probably add some more details about the world as a whole.
The world is not one single, uniform biome. Although generally speaking the planet is more desert-like than Earth, the poles are, as one would expect, freezing wastelands almost year-round, while the equatorial region is essentially a scorch zone. Any reasonable group of settlers would probably find it easiest to survive right in between the two. Some regions contain more water than others, and while oceans as we know them do not exist, I'll say for the sake of the question that relatively small, saline seas pockmark the planet as well.
"Earthlike" flora and fauna is relative. Obviously you won't see penguins waddling about the surface of my planet, but creatures and plants similar to those of Earth's harshest deserts, with various adaptations to maintain homeostasis despite the environment, do exist.