A government based on the peaceful principles of Confucianism and Daoism, plus the defeat of the Xiongnu invaders from the north allowed ancient China, under the Han Dynasty, to experience a period of time known as .

less available tax revenue

this basically means that when they get money from taxes wirth having a lower gdp they get less then what others have with a higher gdp

after the aryan's settled in india they changed for the better i bellieve they changed from nomads having to keep moving to being farmers   they were aswell avaible to turn the ganges river into farmland.   which is great they added a big affect on farming as we know of it today.

d. both had been uninhabited before settlers arrived.