Before the mid-twentieth century, villagers, pastoral
nomads, and urbanites were part of a framework of trade
relationships that was generally beneficial to all. A geographer
called these relationships the “ecological trilogy.” The village
peasant farmers were the cornerstone of the trilogy. They grew
the cereal grains, fruits, and vegetables that fed city people.
Desert pastoral nomads also ate farmers’ produce, buying flour,
for example, when they visited towns periodically to sell their
livestock. Villagers benefited in that exchange. Because they
often lacked enough land to support animals like sheep and
goats, by trading with the Bedouins they could get these ani-
mals’ meat, hide, horn, milk, wool, and bone. City people, too,
gave something back to the villagers in the form of education,
trained medical providers and equipment, and entertainment
such as music.