Why is Ban Ki-moon referred to as Mr Ban in the media and not Mr Ki-moon?

[Hen Field Honey Co.]

If my name in England were Mr Dennis Wise then I would be referred to as Mr Wise, not Mr Dennis. I assume it is a cultural difference but if anyone can clearly explain this cultural difference I would appreciate it.

 

[Bill]

Because in most East Asian cultures the family name (i.e. last name) comes first.