The ceremony in which men became vassals to their lord was called:

The correct answer is:  

Homage.  

Homage was a ceremony developed in the Middle Ages. In this tradition a feudal tenant or vassal promised reverence and obedience to his feudal lord, getting in exchange the symbolic title to his new investiture. It was a symbolic recognition to the lord, claiming that the vassal was his.  

answer; i believe the correct answer is (the willamete valley);

the conditions that made the byzantine empire vulnerable to attacks by the muslin turks were the sack of constantinople by western crusaders, the conquests of the sultanate of rum, presence of rival kingdoms and finally the set up of fiefdoms at the empire which were owned by the ghazis (turkish warriors).