Orcs can't be Turks. No horse archers. Their military is totally different from them, they suck at fighitng (thus can't be Turks), and I think that they represent far more the evils of any group of people, rolled into one.

P.S. If there are wrong translations with according to the proper nouns used in the book (i.e. is the Orcish language called black language really?) . I did not ever read the book.
Eh, it might be mentioned somewhere in the appendices. It's not officially called "The Black Language", though.