Rebel of the sands / Alwyn Hamilton.

Enhanced descriptions from Syndetics:

"You will cheer for Amani the whole way as she escapes the bonds of oppression and finds her own power, and you will mark your calendar for the sequel."--Rae Carson, bestselling author of the Fire & Thorns trilogy

Mortals rule the desert nation of Miraji, but mythical beasts still roam the wild and remote areas, and rumor has it that somewhere, djinn still perform their magic.  For humans, it's an unforgiving place, especially if you're poor, orphaned, or female. 

Amani Al'Hiza is all three.  She's a gifted gunslinger with perfect aim, but she can't shoot her way out of Dustwalk, the back-country town where she's destined to wind up wed or dead.

Then she meets Jin, a rakish foreigner, in a shooting contest, and sees him as the perfect escape route. But though she's spent years dreaming of leaving Dustwalk, she never imagined she'd gallop away on mythical horse--or that it would take a foreign fugitive to show her the heart of the desert she thought she knew.

Rebel of the Sands reveals what happens when a dream deferred explodes--in the fires of rebellion, of romantic passion, and the all-consuming inferno of a girl finally, at long last, embracing her power.