The 'sand desert' is, as its name implies, dominated mostly by sand. Many of these so-called sand deserts are also badlands or areas with less than an inch of rain each year.

Example encounters include:

Kobolds (4E Dungeons and Dragons Monster Manual)
Large Scorpions
Giant Toads
Hatori
Slicer Beetles
Antari Lion
Bulettes (4E Dungeons and Dragons Monster Manual)
Srik
Minotaur Lizard