I don't know where you got news that economy is transitioned to bitcoins in bangladesh.Using bitcoins is banned in bangladesh.Even people are imprisoned if caught using bitcoins.But african continent have a large number of countries with huge population.Their economy is not that much good.Money transactions was made possible in bitcoins there with m-pesa.It became a big success there.But that same strategy would not be successful in all countries.For example,unless bitcoin is legalized like japan,economy could not be transitioned to bitcoin.