I had been reading about cities of Silk Road (Merv, Balkh, Khorasan, Buchara etc). Large, rich cities surrounded mostly by hostle enviroment (desert, dry steppe

I had been reading about cities of Silk Road (Merv, Balkh, Khorasan, Buchara etc). Large, rich cities surrounded mostly by hostle enviroment (desert, dry steppe). They had always inflow of citizens and stratified social structure. Wars and plagues opened possibilities for social mobility however. Elites died same as poor people (or more in times of conquest) and that opened possibilities for lower class individuals to move up.