Next up along the Silk Road is Qinghai Province (formerly known as Kokonor). Although fourth-largest in size, Qinghai is the third-to-last of all provinces population-wise.
Xi'an is known as the ancient capital of China because it is one of the oldest cities in the country, the capital of both the Han and the Tang Dynasty, the starting point of the Silk Road and the home of the burial mounds of many historically important emperors (and one empress). Today, it's become a historically rich and vibrant city, home to 8 million people.
Qingdao, known as China's Sailing City, is both a major port and an industrial centre situated right on the east coast of China in Shandong Province (China has thirty provinces -- they're kind of like the states here in the U.S.). In Chinese, Qingdao means "greenish-blue island," and that description is entirely true.