The Middle East desert experiences extreme temperatures, with summer highs over 120°F and winter lows below freezing. Rainfall is very low at only 3-4 inches annually, and droughts can last for years. Rare, violent storms can cause flash floods. Nomadic Bedouins migrated with their herds of sheep, goats and camels, setting up tents at oases where fresh water allowed plants and crops to grow. As some nomads settled at oases permanently, towns evolved that grew dates and grains and became trading centers for nomadic goods. Coastal areas and mountains received more rainfall and had farming communities and terraced crops.