Sultanate of Oman
From the late 17th century, the Omani Sultanate was a powerful empire, vying with Portugal and Britain 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 (today part of Tanzania, also former capital). As its power declined in the 20th century, the sultanate came under the influence of the United Kingdom. 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. Oman's official religion is Islam.