Orc

Thousands of years before humans came to Khorvaire, the land was dominated by wild orcs and goblinoids of the Dhakaani Empire. The goblin empire scattered the orc tribes and forced them into harsh and unwanted lands: the swamps of the Shadow Marches, the Demon Wastes, and the depths of the Ironroot Mountains. But in the Shadow Marches, the orcs learned the secrets of druidic magic from the dragon Vvaraak, becoming the first of the Gatekeepers. With the invasion of the alien daelkyr from Xoriat, the Gatekeepers put the dragon’s teaching to the test, creating magical seals that bound the daelkyr in the depths of Khyber and protected Eberron against further incursion from the plane of madness. Three prominent groups of orcs have survived into the present age:

The Ghaash’kala are servants of the Silver Flame (which they call Kalok Shash, the “binding flame”), who devote their lives to battling the fiends of the Demon Wastes. Humans from the Carrion Tribes of the wastes sometimes hear the call of Kalok Shash and join the Ghaash’kala, leading to a significant population of half-orcs there.
The Jhorash’tar orcs are a perpetual threat in and around the Ironroot Mountains, shaped by their resentment of the Mror dwarves who drove them underground. These orcs are isolated from humans, so half-orcs here are rare.
The Shadow Marches holds the largest numbers of orcs and the most significant population of half-orcs.