Ironskin Tribe

The Ironskin Ogres are a fierce lot, known for their hard--hitting charges and their penchant for black iron gut-plates. The tribe's specialty is to launch massive avalanche-like attacks onto their foes, smashing into them in a single sweeping crush. During such assaults, they always seek to grab as many prisoners as they can, and then march them quickly home into their deep valley in the north-western range of the Mountains of Mourn. So prodigious and successful are these attacks that the Ironskin tribe has thus established strong ties to the citadel of Zharr Naggrund, whom they trade with to obtain their armour and, as rumours have it, the great mechanical beast ridden by their Tyrant, Ghark Ironskin.

Source

 * Warhammer Armies: Ogre Kingdoms (8th Edition) -- pg. 21