Complex sentence: Sayf al-Dawla played also a crucial role in the history of Aleppo and Mayyafariqin, as his choice of these two cities as his capitals raised them from obscurity to the status of major urban centres.
Split into simpler sentences: Sayf al-Dawla was also important in the history of Aleppo and Mayyafariqin. His choice of these two cities as his capitals raised them from obscurity to the status of major urban centres.