The Chronicles of Conan Volume 27: Sands Upon the Earth — Dark Horse Comics

"He is known as ""The Great Devil""--Heku, warlord of the eastern kingdoms, commander of a horde likened to the sands upon the earth. More than conquest, Heku desires the return of his son, Kobe, once coldly given as a gift to a king but now Conan''s comrade and unwilling to return to his father''s evil embrace. All Kobe has between him and Heku''s host is his sword and Conan''s friendship, a bond stronger than steel! 
The Chronicles of Conan collects classic Conan the Barbarian tales never-before collected and unavailable for over a quarter of a century."