Since many centuries ago, the best mind in mankind scholarship tried to answer the question of why some countries are rich, and some are poor. Ibn Khaldun, Adam Smith, and Karl Marx gave their analysis. But, cross country data were not available. Economists right now can obtain new conclusions by observing many cross-country data, including data about colonialization. The data shows that colonialization has multi-effect: some good and most of them bad and ugly. Some make countries really rich (US, Australia, Canada), and most of the former colonies are extremely poor: Congo, etc.
What makes this research great? Because the simplicity of their arguments and their sophisticated way to prove that arguments. Moreover, they try to answer one of the most important question in Economics, “Why Some Country Prosper while Others Not?”