In the center is the city, surrounded by market gardening and dairying, followed by a region of forest. This is then followed by mass production fields making goods such as grain, which is followed by ranching and livestock on the outermost ring. After this is wilderness, or so Van Thunen thought, as after this he found it was too far from the nearest city to be profitable. He attempted to use this model to explain why agriculture occurs where it does relative to cities despite having similar natural conditions around it.