6. Osman Ali Khan: $ 230 billion (217 billion euros)
Born April 6, 1886 in Hyderabad, a former state from central India, and died February 24, 1967 in the same city, it is the last reigning monarch of the dynasty of the Nizam of Hyderabad and Berar (the one of five sultanates of the time). He has the reputation of being the richest man in the world in his time. Despite this he led a rather simple and frugal life.