Yael was born in a tribe of nomads who tended horses, in the steppes of modern day Russia. As was custom among her people, she learn to bear arms and achieved great skill with the bow. After being embraced into the Salubri, she put those skills to good use fighting against the infernal wherever she could find them.
It is said she made a great many journeys to dangerous places seeking knowledge about the Evil's servants, and one of such journeys brought her to Matthias, a follower of the path of the healer.
The pair quickly became close friends, for Matthias acted as her chronicler and advisor as well as a constant companion. They fought Baali and Setites infiltrated into the Church, and were also responsible for pinning down a great deal of the history of the Salubri in their battle against the Baali and other Infernalists.
It is unknown what happend to Matthias and Yael, but many believe that her zealotry would eventually set them in a collision course with the Tremere.
Clanbook: Salubri, p. 40, 64