I do not think this ban is being happened for your country. Ban is happening for policy violation which is mentioned on the forum rule. Better check forum rules properly.
There is obviously no ban on the OP's friends per se,he only came up with a sort of cryptic post to find out why they were banned I guess.
Or it's either the OP and his friends didn't read the rules,or are totally oblivious of rules and do not even know what's a ban message.
Anyways it seems OP and his friends are all plagiarist,so OP has been added to the banned list, as he/she also cannot access the forum from Vietnam anymore