Complex sentence: Xenia Godunova, the daughter of Tsar Boris Godunov, also became a nun here in 1606, before being transferred to the Knyaginin Convent in Vladimir.
Split into simpler sentences: Xenia Godunova, the daughter of Tsar Boris Godunov, was presumably made a nun here in 1606. Subsequently, she was transferred to the Knyaginin Convent in Vladimir.