The Calormene girl who escapes with Shasta in The Horse and His Boy is Aravis.
Aravis is a young Tarkheena, a female member of Calormen’s ruling nobility. She flees because her father has arranged her marriage to Ahoshta Tarkaan, a powerful courtier she despises. Her talking mare, Hwin, reveals her Narnian origins and persuades Aravis to seek freedom rather than take her own life.
During the journey north, Aravis meets Shasta and the talking horse Bree. Although the pair initially dislike each other, they travel together and discover a plot by Prince Rabadash and the Tisroc to invade Archenland. Their warning allows King Lune and the Archenlanders to prepare for the attack.
Aravis is sometimes confused with Lasaraleen, her Calormene friend who helps her escape through Tashbaan. Lasaraleen does not make the northward journey with Shasta. After Shasta is revealed to be Prince Cor, he and Aravis eventually marry and rule Archenland; their son is Ram the Great.