Does it ever say in War and Peace what happened to Princess Bolkonsky? Did she die having Marya? When Andrei and Marya were young? Sometime during Andrei's early adulthood? Or does it just not say? Or maybe she's alive the whole time and Tolstoy just casually forgot to name or mention her.
we know, at the very least, One Thing about the late princess bolkonskaya, and it’s that she safely gave birth to marya in a small town (i’m guessing) called kisheynov with only the assistance of a “moldavian peasant woman” (book two, part one, chapter 8). it’s assumed that she died when the bolkonsky siblings were both very young—aside that, we know Nothing, which is such a shame, because marya and andrei had to have gotten all their good character traits from someone !!