Update : ussr: south korea, south vietnam, invasion of eat germany, pol pot, mao ...show more

Update 2: @empty:you are right communism killed 100c milion of people but ...show more

Instead of asking random strangers on the internet, why don't you act like a responsible adult and do some actual research? There are plenty of books and encyclopedia articles on the history of mathematics and numbers systems. Get off your butt, go to the library (or use the library website's online resources), and find out from a reliable source.

Usually the initial change was a result of military conquest. Someone basically showed up one day and said "my land" and in the case of a few countries in eastern Europe "my people."

After that it was often a result of taxation systems which put an undue burden on small landholders and favored large landholders who usually gained exemptions through providing military forces. Free peasants facing bankruptcy and slavery often married into serfdom.