In J.R.R. Tolkien’s mythology, what language contains the inscription on the One Ring?

The inscription on J.R.R. Tolkien’s One Ring is written in the Black Speech of Mordor.

The inscription begins, “Ash nazg durbatulûk,” meaning “One Ring to rule them all” in the poem’s English translation. It is a portion of a longer verse describing the Rings of Power and their relationship to the One Ring. Sauron created the Black Speech for the servants of Mordor.

The letters on the Ring are Tengwar, Tolkien’s script, which can represent multiple languages. This creates a frequent mix-up: Tengwar identifies the writing system, while Black Speech identifies the language of the inscription.

Tolkien supplied only limited examples of Black Speech. The language is therefore much less extensively developed than Quenya or Sindarin, the best-known Elvish languages. The Ring’s words were spoken in Orodruin, or Mount Doom, where Sauron forged it during the Second Age.