Rangers of the North
Orcs are described as ugly and filthy fanged humanoids. The largest can reach near-human height, but they are always shorter, and some are as small as Hobbits. In contrast, crossbreeds between Men and Orcs are called “man-high, but with goblin-faces.” However, some Orcs are very broad, if not tall. Many Orcs have long arms, like monkeys or apes. Many of them also have crooked backs and legs. No one knows how old Orcs can grow – certainly hundreds of years – but due to their brutal and violent lifestyle few make it beyond fifty years of age.
The Orcs in Eriador are mainly Angmarrim in origin, descending (or hailing from) the War in the North, when the Witch-king unleashed his hordes on the men of Arthedain, Cardolan and Rhudaur.
Twelve tribes of Orcs under the sway of Angmar formed a loose confederation called the Yrch Angmar.
The Empire of the Witch-king stretched deep beneath the Misty Mountains. It included a number of quasi-independent kingdoms, the most notable being the realms ruled by the Lords of Goblin-gate and Mount Gundabad. These fiefs provided the Witch-king with thousands of troops, but their armies normally operated independently.
The vast majority of the Witch-king’s main war host was composed of Orcs. Collectively known as the Yrch Angmar, this Orc army was a loose collection of nine tribal confederacies held under the terrible sway of the Olog warlord Rogrog. Many of the thirty or more tribes made war on one another, and such inter-tribal raiding forced the Witch-king to keep them apart whenever possible. Twelve Orc-tribes were scattered across the long frontier with Arthedain, and two occupied the passes between Gundalok and the Nan Angmar. The rest resided in vast cave complexes like those in Carn Dûm and Mount Gram, or in the lesser cavern systems in the karst around the edge of the Vale of Angmar.