"The Lost Valley of Iskander" is an El Borak short story by Robert E. Howard. It was not published within Howard's lifetime, the first publication was in the FAX Collector's Editions hardbackThe Lost Valley of Iskander in 1974. Its original title was "Swords of the Hills".
In this story, El Borak discovers a legendary valley in which live Greek descendants of Alexander the Great invading army. Meanwhile, the vital package he carries must be carried to British India before the Hungarian, Hunyadi, can stop him or thousands will die.