1500 years before Mohamed, long before there was a Persian empire, Iran was home to an advanced civilization, both socially and technically. With only about 2/3 as much annual precipitation as Los Angeles, they engineered and constructed a vast system of underground aqueducts, called Qanats. They were underground in order to avoid evaporation losses, and they were networked from the mountains down to the cities with a constant, gentle downward slope because electric pumps were not an option, and camels had better things to do.
Multiple wells were linked by the network. Without the qanats, agriculture would have been out of the question, and the region would have been home only to nomads. There are 37,500 qanats remaining in present-day Iran, from a former peak of more than 100,000.
The ancients were also accomplished at storing ice from the winter to be used all summer. This structure is called a Yakhchal.