As you get to the end of the 11th century, the Crusades began. And we'll do more videos detailing the Crusades where the Western kings start sending folks at first on the surface to try to help the Byzantines reconquer land from the Muslim empires. But even when they are successful, they don't give that land back to the Byzantines. They actually set up crusader kingdoms. And as they make their way through the Byzantine Empire, they cause, for the most part, a bit of a stir. They're not particularly respectful through the lands that they pass. And it really comes to a point in 1204 where at the end of the Fourth Crusade, the crusaders actually decide, even though the purpose was arguably to reclaim land from the Muslims, the crusaders decide siege and sack Constantinople itself and take over.