Why is it useful for historians to base certain studies on the analysis of historical themes

since most of current immigration into the u.s., both legal and illegal, is coming from latin america. it would be very difficult to imagine or rationalize a country my fellow citizens are trying desperately to flee into, would pose a threat to my prosperity or freedom. since the u.s. has a long history of intervention, but no record of permanent occupation, i would not feel oppression is the main objective.  

the largest free trade nation, along with the largest gdp in the world wanting to expand it's economic policy on us, and including us, could only be positive. the u.s. government has no interest in, or way of simply forcing american culture on us. and has no track record of it. other nations that adopted american social culture, or "americanization" did so voluntarily, mainly through the choice of allowing american businesses and u.s. citizens to come into their nations, as free operatives.

answer: both considered peasants valued members of society.

explanation: the ancient chinese and indian empires were large asian empires that had the same problems with other big empires, they had to work hard and sometimes fight in order to keep them united, they both relied heavily on their capacity to trade and to send strange and rare items to europe, and had the father as the head of the house hold in both societies, but they didn´t considered pleasants as valued members of their society, they were the bottom of the social pyramid in both of their societies.