What advice given by Ibn Khaldun might be useful for merchants even in the 21st century?

cultural/diplomatic relations. most medieval japanese   culture has chinese origins. writing, architecture etc.

this isn't a question and if you're going to list things be kind and use commas.

the noble might have thought that the system was far because they had lot of things and riches and the serf would have thought that the feudal system was un fair because of the way they were treated.