The possessive form for the singular noun emperor is emperor's.
example: The one who really rules the castle is the emperor's wife.
Emperors' The word emperor, like almost all English word, merely requires an s to be affixed to the end to become plural. And, like almost all English plural nouns ending with an s, the apostrophe simply goes after it rather than before (as in the case of singular possessives).
The emperor ruled the county. He was the emperor of China. Some countries have a president or a monarch instead of an emperor.
The Roman emperor had to answer to the pope.
The government form in China in the middle ages was Dynasties. They were NOT successful.
world's
The singular possessive form is week's.
The singular possessive form is classmate's.
The possessive form is Amos's.
The singular possessive form for the noun gypsy is gypsy's.
The singular possessive form for country is county's.
The singular form for the plural noun countries is country; the singular possessive form is country's.
singular possessive: boy'splural possessive: boys'
The singular possessive form is speculum's.
The singular possessive form is contralto's.
The singular possessive form is frontiersman's.
The singular possessive form is aircraft's.
The singular possessive form is herd's.