Any idea what this passage is referring to?

I am currently reading a book and this passage is specifically talking about a woman from Zanzibar who pulls something out of/from beneath her "Aba" and I was curious what it looked like and CAN NOT find anything. Any one willing to educate me? This is the passage..."However, my demonstration had made an impression, especially on the third member of the party, an older woman, who argued with the other guy a bit and evidently carried the point; she brought a small flat black sack out from under her aba and tossed it over the statue—the sack remained the size of a small handbag, but the statue vanished into it completely—and then gave one of the handles to the fighter."