Complex sentence: Conrad the Red was married with Luitgard, a daughter of Emperor Otto I, their son was Otto, Duke of Carinthia 978-1004 and his sons were Pope Gregory V, Henry, count of Speyer, and Conrad.
Split into simpler sentences: Conrad the Red was married with Luitgard, a daughter of Emperor Otto I, their son was Otto, Duke of Carinthia 978-1004. Otto's sons were Pope Gregory V, Henry, count of Speyer, and Conrad.