In 1105 Nuremberg Castle and the city of Nuremberg were partially destroyed during the conflict between Emperor Henry IV and his son Henry V. In order to better protect the castle and the city in the future, Henry IV appointed the brothers Gottfried II and Conrad I of Raabs as burgmann of Nuremberg castle, with the title official of "Castellan". Thus, they became the first de facto Burgraves of Nurembert. Gottfried's son Gottfried III was the first member of the family to be called burggravius of Norimburg in an official document.
After Gottfried II died, around 1137, Conrad I ruled Nuremberg alone. After Conrad's death, Gottfried's son Gottfried III inherited the Burgraviate.
References
Sigmund Benker and Andraes Kraus (eds.): Geschichte Frankens bis zum Ausgang des 18. Jahrhunderts, founded by Max Spindler, 3rd ed., Beck, Munich, 1997, ISBN3-406-39451-5