emirate; sheikdom
A political territory ruled by an emir or sheik; commonly used in reference to the United Arab Emirates (アラブ首長国連邦).
The United Arab Emirates consists of seven emirates.
首長 is the ruler (emir, sheik, or chief), while 首長国 is the territory they rule.
Compound of 首長 (shuchō, 'chief, emir') + 国 (koku, 'country'). The term is a modern coinage used to translate 'emirate'.