The Rythanko was a magical bracelet of unknown origin. It was carried by a Githyanki aboard a merchant ship on the Moonsea when the ship was captured by the Orcsblood in 1460 DR. A young pirate named Gareth Jadaren took the Rythanko from the Gith and carried it to Mulmaster after he deserted his ship.
Gareth paid a mage to identify the Rythanko but the mage claimed it was worthless even though he knew it was very powerful. Later, Jandi M'baren used the Rythanko to create the wards on Jadaren Hold.
The full extent of the Rythanko's powers are unknown but it seemed to control the pocket plane that the entity Fandour was imprisoned in and some of Fandour's power seemed to be linked to the Rythanko. The bracelet appeared to be semi-sentient and could alter its shape to avoid detection.