Who is the true African American?

I may have asked this a few years ago, but it comes up every few years, so I will give myself the benefit of the doubt and ask again since it happened again.

My girlfriend was born in Egypt. She is a dark skinned North African Arab.

She came to the US in order to go to medical school, and stayed here. She is, shall we say, feisty.

Last weekend we went to an event in San Diego, and a black guest who is third generation LA told her, in a typical cocktail party debate about social justice, that she had no idea what it is like to be an African American.

She told him that between the two of them, she was the only true African American present.

He took offense to this. She can handle herself, so I stayed out of it, in spite of myself.

So who gets to claim the description African American.?
If it isn’t anyone who comes to America from Africa, who is it?