The Orcs of Angmar (Or."Uruk-Ongmair") originally were a coalition of Orc Tribes from the northern Misty mountains and the surrounding lands which had been pressed into the service of the Witch-King of Angmar.They counted more than twenty tribes of which the Askhai, Bagronkuz, Durbalag, Faulgurum, Kurkurûm, Larag-Mosh, Lughoth, Skuthrugai, Snagoth, Skuthrugai, Sulmog-Vras, Thopur-Dorashk, Thrakburzum, Trupalog, Ulogarum, Uroth-burm, Urughash, Uruk-kosh, Uruk-Lûgat, Uruk-Uflag and Zem-Vishturak were the best known.
With the Fall of Angmar in the 20ieth century of the Third Age the coalition fell apart and so did many of it's tribes which either had been slaughtered or dissolved into warring clans.In the late Third Age , Agents of Mordor had tried to reorganize the Orcs who lived within or near the borders of old Angmar and formed a federation of seven greater Orc and Troll tribes which included the Blogmal, Ghâshfra, Hontimurz, Kraiarn, Ongbúrz, Tarkrîp and some Ghâsh-Hai.