The Great Hunt (The Wheel of Time #2) by Robert Jordan

Goodreads Synopsis
The Wheel of Time turns and Ages come and pass. What was, what will be, and what is, may yet fall under the Shadow. For centuries, gleemen have told of The Great Hunt of the Horn. Now the Horn itself is found: the Horn of Valere long thought only legend, the Horn which will raise the dead heroes of the ages.

And it is stolen.