When Sauron made the Ruling Ring at Sammath Naur, he also caused lesser rings to be made, the Nine and the Seven, which were under the power of the power of the One. Althougth the three elven rings were hidden from him, the Seven dwarven and Nine mannish rings came under his control, and those to whom he bestowed them, became his creatures.

The nine wearers of the rings of men became great lords in their time, but their worldly power was achieved at a terrible cost. For their lives were preserved indefinitely, and eventually after countless years they became mere shadows, animated by the will of Sauron, their sole purpose to do his bidding. Without their raiment they were virtually invisible to the naked eye; however, Frodo saw their true shapes when he entered their realm, by putting on the One Ring.

The Ringwraiths were the Dark-lord's most terrifying servants, and so closely were their fates tied to his that he could count upon their complete loyalty. Thus, when at the outset of the War of the Ring, Sauron was searching for the Ringbearer, it was the black-clad Ringwraiths that he sent to scour the Shire and the road to Rivendell. They came to the Shire mounted on black horses, specially trained to accept their spectral riders but later when these mounts were destroyed at the fords of Bruinen, they were provided by Sauron with fell winged beasts.