Scarlet Monastery was in the Tirisfal Glades to the northwest of Undercity, the northeast of the spawn place for undead players.
For undead players who liked to explore the land, they had found this place long ago. But due to its difficulty level, players lower than level 30 couldn't possibly pass it, which was why no one had wasted time on this higher-level instance even though they had found it.
Only players over level 30 could enter and explore it.
Different from the Deadmines, which solely belonged to the Alliance, and the Wailing Cavern, which solely belonged to the Horde, Scarlet Monastery was accessible to both Alliance and Horde players under the instruction of their quests. Of course, since it was closer to Undercity of the Horde, it was friendlier to Horde players.