The subject of this article originates from non-canonical sources. To find out about what is considered "canon" see LOTR:Canon.
The Earth-kin of Middle-earth (or Jorkyn, pronounced Yorkin, as they called themselves) were a peaceful, tribal, Giant-type of beings. They mostly inhabited Eriador and were scattered around the Lone Lands and North Downs.
The Earth-kin were hunter-gatherers and shepherds, and made dwellings around ancient stone structures like henges. They kept flocks of aurochs, and fiercely defended against any attack made on their livelihood of herding. Although peaceful in nature, they were ready to stand up against any who threatened their homes.
The Earth-kin stressed to visitors and diplomats sent by the Free Peoples of Middle-earth that they wished to remain practicing their way of life as they always did, and that meddling in the affairs of the "little ones", as they called Men and other folk, was not their interest. Yet some Earth-kin were persuaded to join in the affairs of Middle Earth, specifically, Angmar. Indeed, it saddened the hearts of all the other tribes of the Jorkyn to find out that a neighboring tribe of Earth-kin that lived in the North Downs had sided with the Witch-King of Angmar. Many attempts were made by the Rangers of the North to bring back this vital tribe of Jorkyn to the Free Peoples, although whether the Rangers succeeded is not told.
- The Earth Kin Description at The Lord of the Rings Online