The Lion's Daughter (Loretta Chase, 1992) isn't your usual historical romance novel. It's set mostly in Armenia, for starters, though the action eventually moves to England (the year is 1818). It's at least as much adventure story as romance, which is never a problem for me.
I enjoyed it, but it's not Chase's best work, IMO. (I'd say her best is Mr. Impossible, but that's a minority opinion. Many readers I know say Lord of Scoundrels is not only her best book, it's the best historical romance they've ever read, period.) Still, average Loretta Chase is still thoroughly readable. I may have been mildly bothered by the age gap between the hero and heroine--he was 28 and she 18--especially since he spent most of the book thinking she was younger still, even while he lusted after her. (It's not that I think there's anything wrong with a ten year age gap per se. I'm planning a couple with a ten-year gap in my WIP series, but they're more like 40 and 30 when they hook up. I'm just not a big fan of double-digit age gaps when the younger partner is still in her teens.) And I may have thought the plot a bit convoluted and hard to keep track of. But I still enjoyed it, and if you're looking for an adventurous romance in an unusual setting, give this book a try.