There are five Black Metal bands with the name Angmar.
Angmar is a realm in the northern part of the Misty Mountains in the north of Middle-Earth, which is being ruled by the king of the Nazgûl in J.R.R. Tolkien's works.
Also Angmar means "house of iron" in Sindarin, an Elvish language created by Tolkien.

1) The first are Finns, who started the project from 1994/1995 and changed band's name to Angmar in 1997.

Read more about Angmar on Last.fm.