Paradoxically, while I am a huge fan of the history of the Medieval Middle East (in particular, of the Eastern Roman Empire) I didn’t watch "Kingdom of Heaven" in the theaters. Instead, I waited for a sick weekend and rented it from the local store.
Ridley Scott set out to do a relatively accurate depiction of the goings-on during the destruction of the Kingdom of Jerusalem. For those that don’t know, in 1099 the First Crusade marched into Jerusalem and captured the city from the Saracens (Muslims). A hundred years later, the resurgence of Islam that came from the Turkic tribes of Anatolia forced the destruction of the Christian Kingdom of Jerusalem.
Just as the notorious internecine warfare between Muslim states enabled the Christians to gain land, their own constant dissonance was their undoing when the Muslims found their unity under Saladin. Indeed, most of the movie tries to deal with this disconnect: a small country on the border of giant empire, and yet its inhabitants are constantly at odds with each other.