The incredible Hulk #92
They possessed the capabilities to create Stone Starships.
The Shadow People appeared as giant humanoids with gray-skinned that resembled metal or a metallic finish.
Ten thousand years ago, Sakaar was already a dying planet, ravaged by Earthquakes, and destined to crumble into pieces that would eventually fall into the sun. However the wandering Shadow People in their great Stone Starships stumbled upon this hopeless planet. For countless years they were in search of a world in need of their special talents. For the healing of such a planet was their gift and purpose. The Shadow People possessed the ability to use the Old Power to reach through the earth, stone and magma of the sick and dying planet to touch and soothe and heal the broken world.Living in the deserts and steppes in which the Empire had little interest, the Shadow People were largely unaffected by the wars between the Imperials and the rise of the Empire. But with the arrival of the alien invaders known as the Spikes, the Shadow People faced a threat which could not be denied. The Shadow People united their military forces under the leadership of the great warrior and strategist Hiroim the Shamed, who saved his people from destruction on numerous occasions. But eventually the Shadow recognized the need for the help of the Father Emperor in wiping the Spikes from their lands. The Shadow Treaty represents the first formal agreement ever made between the Shadow People and Imperials. It guaranteed the political independence of the Shadow People and the assistance of the Empire in wiping out the Spikes in exchange for a certain number of Warbound Shadow dedicated to service to the Empire. The Father Emperor chose Hiroim to be his Warbound Shadow: the Father Emperor's son, who later became Emperor himself, chose a young female Shadow warrior known as Caiera the Old Strong, who served as his first lieutenant and personal bodyguard.