Short answers, pulled from the story.
East Asia includes China, Japan, Mongolia, North Korea, South Korea, and Taiwan, plus the two special administrative regions of China, Hong Kong and Macau. The economies of China, Japan, South Korea, and Taiwan are among the world's largest and most prosperous.
East Asians make up about 33 percent of the population in continental Asia and 20 percent of the global population. The overall population density of the region is 133 people per square kilometer, about three times the world average of 45.
China was the first region settled in East Asia and the core from which other parts of the region took shape, exerting cultural, economic, political, and military influence for over two millennia. East Asian vocabularies and scripts often derive from Classical Chinese, and the Chinese calendar is the root of many other East Asian calendars.
The Meiji Restoration transformed Japan from an isolated feudal state into East Asia's first industrialized nation, after Commodore Matthew C. Perry opened the country to Western influence. Japan defeated the Qing dynasty in the First Sino-Japanese War and defeated Russia in the Russo-Japanese War in 1905, the first major modern victory of an East Asian power over a European one.
The People's Republic of China was proclaimed on the 1st of October 1949, after the Communists defeated the Nationalist Republic of China government, which retreated to Taiwan. The Korean War followed from 1950 to 1953, hardening the northeast along communist and anti-communist lines.
East Asia has grown warmer with more frequent and severe heatwaves, and its monsoon is expected to intensify and bring more flooding. Guangzhou is projected to face the single largest annual economic losses from sea level rise in the world, potentially reaching US$254 million by 2050.