He was a son of Rostislav Mstislavich, appanage prince of Smolensk. He
was appanage prince of Mozhaisk and then of Smolensk from 1278. He is shown on
this family chart of the Smolensk princes. He
married first around 1260 Maria the daughter of Vasilii Vsyevolodovich, appanage prince of Yaroslavl
and heiress to the Yaroslavl domain on the death of her father and brothers.
Thus Fedor became appanage prince of Yaroslavl due to agreement of the princes
of Vladimir-Suzdal. This is shown on this chart.
And when Maria died he retained the appanage. Then he married Anna, daughter of
the powerful Mongol-Kypchak general, Nogai, who controled the entire steppe
from Serbia to the Volga. From his first marriage his son was
Mikhail, appanage prince of Yaroslavl. From his
second marriage his sons were David, appanage prince
of Yaroslavl and Konstantin, prince without udel of Yaroslavl. And he had two
daughters. Although titular prince of Yaroslavl, Fedor had to spend his time
more at Smolensk, so rule passed to his son, Mikhail during Fedor's life. And
when Mikhail died before Fedor the succession then was assured for David.