Imagine an isolated circle-shaped city in a medieval setting. Within this circle is another circle, where the Highborn are living (around 100k people). Common folk (around 900k people) lives on the outter circle, where they are working. My question is, how much space in km^2 or square miles do I need to have in the outter circle for living space, working space, farmland, livestock etc.?
Resources such as water and firewood will be dealt with with magic. I just want to have a rough idea of how much space I need.