The Byzantines, however, managed to stop further Islamic expansion into their lands during the 8th century and, beginning in the 9th century, reclaimed parts of the conquered lands. In 1000 AD, the Eastern Empire was at its height: Basil II reconquered Bulgaria and Armenia, and culture and trade flourished. However, soon after, this expansion was abruptly stopped in 1071 with the Byzantine defeat in the Battle of Manzikert. The aftermath of this battle sent the empire into a protracted period of decline. Two decades of internal strife and Turkic invasions ultimately led Emperor Alexios I Komnenos to send a call for help to the Western European kingdoms in 1095. The West responded with the Crusades, eventually resulting in the Sack of Constantinople by participants of the Fourth Crusade. The conquest of Constantinople in 1204 fragmented what remained of the Empire into successor states; the ultimate victor was the Empire of Nicaea. After the recapture of Constantinople by Imperial forces, the Empire was little more than a Greek state confined to the Aegean coast. The Byzantine Empire collapsed when Mehmed the Conqueror conquered Constantinople on 29 May, 1453.