The term 'Sultanate Gulf' refers to the Gulf of OMAN, which is located in the Middle East and borders the United Arab Emirates, Iran, and Pakistan. The four-letter answer to this crossword puzzle is 'OMAN', which is the country that borders the Gulf of OMAN. The Sultanate of OMAN is a monarchy that has been ruled by the Al Said dynasty since 1744. It is known for its rich cultural heritage and its strategic location on the Arabian Peninsula.