From A Wiki of Ice and Fire
The stallion who mounts the world or Stallion Who Mounts the World is a Dothraki prophecy about an individual who will rise to become the most powerful khal ever seen.
A Game of Thrones
Daenerys Targaryen's son with Khal Drogo, Rhaego, is believed to be the stallion who mounts the world. After Daenerys eats a horse's heart at Vaes Dothrak, a crone of the dosh khaleen proclaims,
||As swift as the wind he rides, and behind him his khalasar covers the earth, men without number, with arakhs shining in their hands like blades of razor grass. Fierce as a storm this prince will be. His enemies will tremble before him, and their wives will weep tears of blood and rend their flesh in grief. The bells in his hair will sing his coming, and the milk men in the stone tents will fear his name. The prince is riding, and he shall be the stallion who mounts the world.
However, Rhaego dies in the womb before any part of the prophecy could be fulfilled.
||The stallion who mounts the world will burn no cities now. His khalasar shall trample no nations into dust.
- Mirri Maz Duur
, to Daenerys Targaryen
References and Notes