Sinthya (pronounced SIHNth-yah) was a noble house of Tortall. Its members have been prominent nobles since the 3rd century HE. The family seems to have the magical Gift, as members in both the 3rd and the 5th centuries were mages.
- Ironwood of Sinthya, the chief mage of King Roger III. Also part of the rebel conspiracy to overthrow Roger III.
- Unnamed lord of Sinthya, committed treason against King Jonathan IV and Queen Thayet
- Unnamed lord of Sinthya, 5 years old
One of Sinthya's members, Ironwood, joined forces with Baird of Conté in his conspiracy, along with other high ranking mages like Lazamon of Buckglen and Orielle Clavynger. Ironwood was not the heir nor the Lord of Sinthya, so there were no repercussions visited on the main line.
Its unnamed Lord in the fifth century of the Human Era made an arrangement with Emperor Ozorne of Carthak to bring immortals to Tortall. He captured Numair Salmalín (in hawk form), but Numair escaped to bring proof to Alanna that Sinthya was dealing with Carthak. The Lord of Sinthya was known to be a weak mage and to dislike Queen Thayet and her Riders.
When King Jonathan went on Royal Progress in Squire, Sinthya was one of the houses, along with Eldorne, Malven, and Tirragen, he stopped at and forced to hold expensive banquets as a punishment for rebellion.