Complex sentence: The city's fortifications were destroyed first and then most of the buildings which, as part of a deliberate policy of "Ayyubidian scorched earth", intended to prevent future Crusades and Crusaders taking foothold in the city and the region.
Split into simpler sentences: The city's fortifications were destroyed first and then most of the buildings. This was part of a deliberate policy of "Ayyubidian scorched earth", intended to prevent future Crusades and Crusaders taking foothold in the city and the region.