The followers of which leader became known as Presbyterian?

When Calvin arrived there in the 1540s, Geneva was a self-governing city of about 20,000 people. He and his followers ran the city according to strict rules. called elders or presbyters Followers of Knox became known as Presbyterians.

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).

where is the subject? hahahaha