Complex sentence: She was presumably born in Ruthenia, in the domains of her paternal grandfather Michael of Chernigov, Grand Prince of Kiev, to Rostislav Mihailovich, future ruler of Belgrade and Slavonia, and his wife Anna of Hungary.
Split into simpler sentences: She was presumably born in Ruthenia, in the domains of her paternal grandfather Michael of Chernigov. Her parents were Rostislav Mikhailovich, future ruler of Belgrade and Slavonia, and his wife Anna of Hungary.