Final answer:
China, situated in East Asia, is separated from the rest of Asia by high mountains, with the East Asian realm comprising China, Mongolia, and others. The Great Wall was built for defense and symbolizes Chinese civilization.
Step-by-step explanation:
China is situated in East Asia, the largest country by both physical area and population in the region. It shares borders with 14 countries and is flanked by the Pacific Ocean to the east. The East Asian countries and territories include China, Mongolia, North Korea, South Korea, Japan, and Taiwan. Mongolia is notable as the only landlocked country in the grouping. China's location has largely been isolated from the rest of Asia by formidable physical features such as the high mountains to the west, which have created a natural barrier that limited interaction and invasion for centuries.
The Great Wall of China was built for defense purposes, to protect against invasions from various nomadic groups from the Eurasian Steppe, including the Mongols. The wall stretches from east to west across the northern borders of China. The Ming dynasty significantly enhanced the wall, especially to protect the agricultural heartland and Beijing, thereby contributing to the meteoric population growth in the 16th century. Its construction was not only a military strategy but also a psychological barrier, known as the Bamboo Curtain, and it has become a symbol of Chinese civilization and endurance.