I'm not sure if the above groups the expert has mentioned are actually considered to be fraternities or sororities themselves, but like he says, many students who do pledge these frats and sororities may also be a part of these groups. But in my understanding, some fraternities and sororities on a given college campus may choose to represent a specific culture or group of people from similar cultures. For instance, you may have an all Asian sorority, or a Hawaiian and Pacific Islander fraternity. Typically, these will most likely only be predominately from one culture, because I believe at some point many fraternities and sororities may still have to meet certain quotas to include some other students of different cultures. But for the most part, they would be known and recognized on campus as that - "The Asian sorority" or the "Russian frat" etc. for example. Mostly these are nicknames though, and really, no matter what frat or sorority you choose, you are likely to find a multicultural mix of some kind nowadays, unless like you say, these are multi-culturally focused on one group.