We know that Dunbar avoids including any specifics in "We Wear the Mask." We also know that he did this on purpose, perhaps with the intention of amplifying his poetic references to masks and deception. But there's no getting around the history and motivation for this particular poem, which is a clear reaction to the stifling racial climate of the late nineteenth century. (Somebody open a window and let some justice in here.)
Race is the ultimate mask in Dunbar's poem (way better than that strip of cloth that the Lone Ranger wears), simply because the world only sees the social stereotypes and stigmas associated with it.
Race isn't the real mask in Dunbar's poem. Nope. The real mask is all of the lies and deceit associated with talking (or not talking) about racial issues.