in the mid-1550s, it represented one of the first trading ports in the Far East. It was later joined by Guangzhou, whose port was the only one remaining open for foreign trade during the closure of the country under the Qing. The Opium Wars brought Hong Kong under British control and forced the opening of other ports in the region. While their respective economic importance was subject to fluctuations later on, the establishment of special economic zones should begin to drive their economic importance anew. Another economic engine in the GBA is the provincial capital of Guangdong province – Guangzhou. Thanks to a rich industrial and high tech economic environment the city was able to attract first US investments such as Coca-Cola, Procter & Gamble, Pepsi in 1990s and to date is the most concentrated area of U.S.-financed enterprises which have invested in southern China. Another milestone in the development of GBA was reached on 18 February 2019 by adoption of the Outline Development Plan for the Guangdong–Hong Kong–Macao Greater Bay Area. The ambitious goal foresees a linkage of the nine cities in Guangdong province's Pearl River Delta, Hong Kong and Macau into an integrated economy and world-class business hub. The document-stipulated crucial milestones for GBA is a formation of the Framework for an international first-class bay area in 2022 and an evolution of the region into an international first-class bay area by 2035. The progress will be achieved through deepening reform, prioritizing innovation, accelerating connectivity, and improving the environmental footprint in the region. In addition, GBA is expected to play a key role in Belt and Road Initiative by connecting Southern China with the countries along the 21st Century Maritime Silk Road. See also Pearl River Delta Pearl River Delta Economic Zone Pearl River Bocca Tigris Metropolitan regions of China Yangtze River Delta Yellow River Delta and Bohai Sea National Central City Special Economic Zones of China South China References Transborder agglomerations Landforms of Guangdong Landforms of Hong Kong Landforms of Macau South China