What is "jingjinji"

Jingjinji or Jing-Jin-Ji (JJJ), also known as Beijing-Tianjin-Hebei, is the national capital region of China. It is the biggest urbanised region in Northern China that includes an economic region surrounding Beijing, Tianjin, and Hebei, along the coast of the Bohai Sea. This emerging region is rising as a northern metropolitan region rivaling the Pearl River Delta in the south and the Yangtze River Delta in the east.