Who is Yanka from Russka: The Novel of Russia and what is their importance?

In 1237, Yanka is seven-years-old. She lives with her parents and brother in the village of Russka when the Tatars arrive and attack her village. Her mother is killed. Eventually her brother Kiy becomes a skilled woodcarver and is taken by the Tatars to work as an artesian for the Khan. After his departure, Yanka, her father and another family flee the area, traveling by boat on the Oka River to the area of Murom, where her father decides to stay on the estate of the boyar, Milei. When she turns sixteen, her father begins an incestuous relationship with her. When the boyar Milei arrives in their village, he is impressed with her and the way she maintains her home. When she asks to travel to Novgorod with him, he agrees and she becomes his mistress. He is kind to her and she is happy in Novgorod. She finds an old woman in the market to abort the pregnancy. While walking around the city, she meets a Mordvinian slave woodcarver named Purgas. Milei pays off Purgas's debt and Yanka marries Purgas. They return to live at Dirty Place and have three children. While walking one day, she sees the Tatar, who killed her mother. She shoots him with his bow and arrow, after which, she and her husband destroy the body.