Just a side-note, that horse is called a Takhi (aka Przewalski or Asiatic Wild Horse). They are from Mongolia & critically endangered (on the threat of extinction), even though they are considered extinct in the wild.
The Takhi is also the "only wild horse" left in the world. In real life, they are completly unrideable & untrainable...so you would never see a person riding a Takhi (only in the manga). For more info about these beautiful rare animals, check out wiki.
Personaly, they're one of my favourite animals & it stinks that they're critically endangered. When we visit the Bronx Zoo at the Bangali Monarail over the river, a large herd of Takhi are there...beautiful in person!