Place of origin:
Tala was a member of the R1C crew under Jackson on its quest to recover the Minyan race banks from the P7E. Tala deliberately tried to end her life by letting herself age to death because she had already lived for centuries.
She regenerated shortly after the Fourth Doctor, Leela and K9 arrived on the ship, then aided in completing the quest. (Underworld)
Behind the scenes
Many of the names and incidents in Underworld were derived from the myth of Jason and the Argonauts. Tala is an analogue of the Greek heroine Atalanta, who was one of the Argonauts in some versions of the myth. (INFO: Underworld, DOC: Into the Unknown)