After the downfall of Númenor, several clans of Black Númenóreans dwelt in the northern mountains of Eriador. In the early Third Age, they rose to prominence under the Witch-king's rule, carving out a kingdom in the hills of Angmar. From their dark master, they learned the ways of sorcery and were taught to create machinery of war far more advanced than anything the primitive Hill-men of the region could build. As such, the Angmarim became the ruling caste and priests of Angmar, worshiping the Dark Lord Sauron as a god. Even after the Witch-king abandoned Angmar following his war with Arnor, the Angmarim remained loyal to the Lord of the Nazgûl and now do his bidding during the War of the Ring.
Angmarim come in several varieties. Some are mere soldiers, while others are High Priests that can summon Fell-spirits from the Void to do their bidding. Some Angmarim can also summon monstrous spiders.
Angmarim are found mostly in Angmar but they are reaching out across Eriador. A significant invading force of them can be found in Evendim in the former Arnorian capital of Annúminas. Another major stronghold for them is the eastern part of the region of Elderslade, before the gates of Gundabar. They are usually "normal" difficulty and are always aggressive. They are usually susceptible to the Westernesse damage type.
Some Angmarim are of Black Númenórean origin, while others are Hill-men recruited to the Witch-king's cause. What sets the latter apart from their common brethren is their use of sorcery and wearing of hooded robes and sinister armour rather than traditional Hill-man apparel. Other Black Númenóreans can be found throughout Middle-earth; these are classified as "Angmarim" though they are not actually from Angmar. Among these are the Umbarrim and the Men of Mordor.
Umbarrim, Black Númenóreans of Umbar, hail from the Havens of Umbar in the distant south along the coast of the Great Sea of Belegaer. They have kinship with the fearsome Corsairs of Umbar who often raid the coastlines of Gondor. Some of these Umbarrim sorcerers come to Angmar, while others dwell in Dol Guldur. Later, the Umbarrim launch an invasion of Gondor.
A few Black Númenóreans of Mordor are directly involved in battles in Rohan and Gondor, but many more can be found in the Plateau of Gorgoroth after Sauron's defeat. Among these are the Gúrzyul, powerful servants of Sauron whom he has made Deathless, and many of their followers; and the Order of the Eye, a cult whose members believe Sauron will return once again. Black Númenóreans in service to the Gúrzyul Karazgar the Weeping Warrior come to Eryn Lasgalen and the Dale-lands, helping their master with some scheme he has for the North.
Black Númenóreans of Mordor would officially be classified as Mordorrim, though this term was sometimes reserved for cultists and sorcerers that served during the Siege of Mordor in the Second Age. Mordorrim cultists can be found in Mordor Besieged during an extended flashback.