The State of Kuwait, or the Dawlat al-Kuwait, can be traced to the establishment of Kuwait City in the 18th century, and was declared officially independent in 1961, whereupon it joined the Arab League. Kuwait is a constitutional monarchy with an elected unitary parliamentary system of 17,820 square kilometers, located at the top of the Gulf, neighbored by Saudi Arabia to the south, Iraq to the north and Iran to the east. Kuwait was a major naval and trade hub that declined until the discovery of oil fields, a resource that has led Kuwait to be one of the richest countries of the world per capita. Kuwait was invaded and annexed by Iraq in 1990, whose military rule came to an end through a US and UN-led military intervention.