Sienna, a female being, was born to Mirienna and Ostar and resided in a village located on the planet of Zeffo. During the Empire's occupation of Zeffo, Sienna's father, Ostar, created a diversion to draw away stormtroopers, enabling Mirienna and Sienna to flee; however, this act resulted in his death. Following this tragedy, Mirienna dispatched Sienna to Chandrila to be with her grandfather, while Mirienna herself became a member of Saw Gerrera's Partisans, though she ultimately chose to depart Mari Kosan's cell to dedicate herself to raising her daughter after discovering her husband's passing.