The "desert" is a theme that runs throughout Scripture. Moses spent forty years in a desert region. Israel spent forty years in the desert before given another chance to take possession of the Promised Land. While being chased by Saul, David lived in the desert. John the Baptist lived and preached in the desert. Jesus spent forty days in the desert being tempted by the devil. Paul, after his conversion, spent time in the desert.
The desert serves as a place where God often tests and transforms his people. Deuteronomy 8:2-3 reveals this as God's intention for the Israelites: "Remember how the LORD your God led you all the way in the desert these forty years, to humble you and to test you in order to know what was in your heart, whether or not you would keep his commands. He humbled you, causing you to hunger and then feeding you with manna . . . to teach you that man does not live on bread alone but on every word that comes from the mouth of the LORD."