Muscat is the capital and largest city of Oman. It is the seat of the Governorate of Muscat. According to the National Centre for Statistics and Information (NCSI), the total population of Muscat Governorate reached 1.28 million as of September 2015. The metropolitan area spans approximately 3,500 km2 (1,400 sq mi) and includes six provinces called wilayats. Known since the early 1st century CE as an important trading port between the west and the east, Muscat was ruled by various indigenous tribes as well as foreign powers such as the Persians, the Portuguese Empire, the Iberian Union and the Ottoman Empire at various points in its history. A regional military power in the 18th century, Muscat's influence extended as far as East Africa and Zanzibar. As an important port-town in the Gulf of Oman, Muscat attracted foreign tradesmen and settlers such as the Persians and the Balochis. Since the ascension of Qaboos bin Said as Sultan of Oman in 1970, Muscat has experienced rapid infrastructural development that has led to the growth of a vibrant economy and a multi-ethnic society.