As I expect this question is based upon opinion, I feel that Paulo Coelho's descriptions of the desert in The Alchemist add meaning to the events at the oasis.
The young boy (Santiago) has already learned about his Personal Legend and the Language of the World by the time he embarks on his trip across the desert with the Englishman. At the beginning of this journey, the boy observes the quiet of the desert, very different than the scene of confusion and noise present as the caravan got organized.
'I've crossed these sands many times,' said one of the camel drivers one night. 'But the desert is so huge, and the horizons so distant, that they make a person feel small, and as if he should remain silent.'
The boy understood intuitively what he meant, even without ever having set foot in the desert before.
The boy first learns to listen quietly, which is part of Coelho's concept of the Language of the World. One must listen in order to hear what nature has to say. Coelho also describes the wind that never stops.
...the boy remembered the day he had sat at the fort in Tarifa with this same wind blowing in his face.
This detail provides a sense of connection between all things in the world. The descriptions of the landscape of the desert parallel life. In some places there were obstacles that needed to be traveled around; some sand was too soft for the camels, so firmer sand needed to be found; the camels would not travel across the dried seabeds, so the men had to carry their burdens themselves and reload them when that space had been crossed: but in every instance, the caravan stayed on course.
But all this happened for one basic reason: no matter how many detours and adjustments it made, the caravan moved toward the same compass point...the star that indicated the location of the oasis.
This description describes life and the traveler. Despite the obstacles life places in one's path, each person must stay on course to discover his or her destiny.
Another description of the setting of the desert adds meaning to the events presented in the story.
...'There are rumors of tribal wars,' he told them.
The three fell silent. The boy noted that there was a sense of fear in the air, even though no one said anything. Once again he was experiencing the language without words...the universal language.
The description here speaks of a sense of fear that is almost tangible. Everyone feels it. There is foreshadowing in this, as danger will visit them at the oasis—as life often presents us with difficulties and/or dangers. However, in terms of the story's themes, the fear parallels the concerns people experience in life from threats known and unknown. This passage emphasizes Coelho's belief that one must listen to the Language of the World, the universal language, in order to find one's way even when that language introduces an element of fear.
I believe Coelho's descriptions of the caravan's journey through the desert add meaning to the events with which the author hopes to instruct his reader.