evidence: Macau, the oldest permanent European settlement in Asia, was returned to China on December 20, 1999. The Portuguese established this port on the southeastern coast of China at the mouth of the Zhu Jiang (Pearl River) in 1557, when they were the dominant power in European trade with Asia. Portugal continued its presence in Macau for more than four hundred years. In December 1887, after a series of negotiations between Portugal and China about Macau's sovereignty, a protocol was agreed upon which recognized Portugal's occupation and governing of Macau. Following Portugal's Revolution of 1974 and China's development of a reunification strategy, the People's Republic of China and the Republic of Portugal issued the Joint Declaration on the Question of Macau on April 13, 1987. This declaration stated that on December 20, 1999, China would resume its exercise of sovereignty in Macau. Now known as the Macau Special Administrative Region of the People's Republic of China, Macau consists of the city of Macau on a small peninsula of the Chinese mainland and the two small islands of Taipa and Colôane, which are connected by a causeway. The entire area of this administrative region is twenty-one square kilometers, which is about 0.1 the size of Washington, D.C. As of July 2001, Macau had an estimated population of about 454,000.