Elemental races most come originally from Calimshan (where is many centuries breeding happening between genies and mortals), far south and across ocean. But the races themselves wander widely and some may come from Thay (thanks in-breeding between elementals and mages/sorcerers). Also some may come from underdark (the earth kind likely). But I could say your background related ifrit may show up anytime or anywhere during the story because she's a wandering elemental raced outsider.