This 1983 Spanish film describes a particular nest of zombies in an oasis in the Sahara, first discovered by German troops in 1942. The Germans buried treasure there and were then (presumably) attacked by a zombie and themselves turned to the undead. A former Allied officer present at the time tried to reach the treasure twenty years later, but was betrayed and murdered by his partner, whose party itself was wiped out by the zombies. The officer's teenage son vowed to find the treasure. Naturally, he trotted off unarmed with friends to the site, against the warnings of local Arab tribesmen who consider the place cursed. Zombie-related havoc ensues, and the teens desperately defend themselves with Molotov cocktails. Two survive.
The film is not as realistic as it could have been, implicitly suggesting that zombies only attack at night and wait until their prey is resting and off guard before striking. In reality, zombies attack at the first sight or smell of fresh meat. However, the film accurately portrayed the normal human reaction to an initial encounter with zombies: fear-inducing paralysis.
But overall, it was an acceptable zombie movie. It is in the public domain now, and you can watch the whole thing here.