Final answer:
The eastern emperor asked for western support against Islam after the fall of Constantinople in 1453, a time when Byzantium sought alliances against the advancing Ottoman Turks, which ultimately led to the launch of the crusades and later stirred the Italian Renaissance.
Step-by-step explanation:
The eastern emperor appealed for western support against Islam after the fall of Constantinople. The Byzantine Empire, once a beacon of cultural and military might, faced significant adversity after its capital city, Constantinople, was captured by Ottoman forces. The eastern emperor's plea for assistance to fight back against the advancing Seljuk and later Ottoman Turks led to Pope Boniface IX's call for a crusade to rescue the Greek Orthodox Christians. This period was marked by political fragmentation within Islam and a quest for military alliances by Byzantium - efforts that ultimately could not prevent the empire's decline and the pivotal fall of Constantinople in 1453 to Mehmed II's Ottoman troops. During the 11th century, the Byzantine Empire faced incursions by Turkic tribes, with the Seljuks and later the Ottomans emerging as dominant powers. The military and political challenges culminated in Alexios I seeking help from the popes, which spurred the crusading movement. The ensuing cultural exchange, however, sparked the Italian Renaissance though it did little to stave off Byzantine losses. The preservation of Greek scholarship by fleeing Byzantine scholars to Italy following Constantinople's fall is seen as a key contributor to the Renaissance.
The eastern Mediterranean underwent a profound transformation with the Ottoman Empire's ascension, highlighted by the conquest of Constantinople, the establishment of Istanbul, and the impact of migration of scholars on the European intellectual landscape.