Oman, officially the Sultanate of Oman , is an Arab country on the southeastern coast of the Arabian Peninsula in Western Asia. Its official religion is Islam. Holding a strategically important position at the mouth of the Persian Gulf, the country shares land borders with the United Arab Emirates to the northwest, Saudi Arabia to the west, and Yemen to the southwest, and shares marine borders with Iran and Pakistan. The coast is formed by the Arabian Sea on the southeast and the Gulf of Oman on the northeast. The Madha and Musandam exclaves are surrounded by the UAE on their land borders, with the Strait of Hormuz (which it shares with Iran) and Gulf of Oman forming Musandam's coastal boundaries. From the late 17th century, the Omani Sultanate was a powerful empire, vying with Portugal and the UK for influence in the Persian Gulf and Indian Ocean. At its peak in the 19th century, Omani influence or control extended across the Strait of Hormuz to modern-day Iran and Pakistan, and as far south as Zanzibar. When its power declined in the 20th century, the sultanate came under the influence of the United Kingdom. For over 300 years, the relations built between the two empires were based on mutual benefits. The UK recognized Oman's geographical importance as a trading hub that secured their trade lanes in the Persian Gulf and Indian Ocean and protected their empire in the Indian sub-continent. By contrast, the British strengthened Oman's internal unity and allied the sultanate against external threats. Historically, Muscat was the principal trading port of the Persian Gulf region. Muscat was also among the most important trading ports of the Indian Ocean. The Sultan Qaboos bin Said al Said has been the hereditary leader of the country, an absolute monarchy, since 1970. Sultan Qaboos is the longest-serving current ruler in the Middle East, and third-longest current reigning monarch in the world. Oman is a member of the United Nations, the Arab League, the Gulf Cooperation Council, the Non-Aligned Movement and the Organisation of Islamic Cooperation. It has sizable oil reserves, ranking 25th globally. In 2010, the United Nations Development Programme ranked Oman as the most improved nation in the world in terms of development during the preceding 40 years. A significant portion of its economy involves tourism and trade of fish, dates, and certain agricultural produce. Oman is categorized as a high-income economy and ranks as the 70th most peaceful country in the world according to the Global Peace Index.