Complex sentence: Moscow, Tver, and Nizhny Novgorod--still contended for the title of Grand Prince of Vladimir, however, once installed, they chose to remain in their own cities rather than moving to Vladimir.
Split into simpler sentences: Moscow, Tver, and Nizhny Novgorod--still contended for the title of Grand Prince of Vladimir. Once installed, however, they chose to remain in their own cities rather than moving to Vladimir.