Complex sentence: In 1248, he married Gertrud, the niece of the last male member of the Babenberg famoly, Duke Frederick II of Austria and brought the Duchies of Austria and Styria as her heirloom.
Split into simpler sentences: In 1248, he married Gertrud, the niece of the last male member of the Babenberg family, Duke Frederick II of Austria. She brought the Duchies of Austria and Styria as her heirloom.