What country do sultanas come from?

Ah! Sultanas! Otherwise known as Thompson Seedless grapes, or white grapes. They are of Turkish, Greek or Iranian origin. You can make a wine from them, but it is very sweet and altogether unremarkable. If you are talking about sultana raisins, they are typically made from sultana grapes. My guess is that if wine is being commercially produced from the sultana grape, it is probably used mostly as a mix to help balance other wines.