The caste systems dates back to the Aryan and Dasas time period. It was used to classify where you stood in the classes or social ranking. There are four classes priest, warriors, traders, and peasants.
Now I understand Politics! When top level people look down, they see only poop-heads; When the bottom level people look up, they see only assholes. You will Never see another Flow Chart that describes politics so clearly.
Politics, Geography and Social Stratification (Paperback)
Labor Markets, Gender and Social Stratification in East Asia : A Global Perspective (Multilingual)