Here the dragonbone lyre is a type of lyre and actually it was used to subdue the guardian of a Shadow Swamp in a plane of shadow in an early 1370s DR.
Description Of DnD 5E Dragonbone Lyre Item
This lyre was the small and fine and seemingly carved from bones of the dragon. Actually, a piece of the parchment tied to gave some of the musical notes and also they read “Play this, and the guardian at Black Tree Bend will subside—Esvele.” Usually, it was worth 800 gold pieces. However it had a haunting sound too.
Even though not magical, a specific tune has been played on the dragonbone lyre would be caused the guardian–a massive zombie dragon turtle-for subside it to back into the depths of the swamp and even let the travellers pass.
In the early days of 1370s DR, the priestess of the Shar Esvele Graycastle could be supplied the dragonbone lyre and also it is tune to the shadar-kai ferrymaster Sithierel so that he could be sailed the Necreme on the Whispermere even untroubled by the guardian she would placed there.
However, it might have been found by the adventurers in the service to the Mystra whenever they came via in early Eleint of the Year of Lightning Storms, 1374 DR.