First, how many people are there? When Qin Shihuang unified the six countries, the total population of the seven countries was about 20 million, which was similar during the Warring States period. As for the specific countries, this is not easy to calculate. Sima Qian's history books are not clearly given, but it can be roughly guessed that the population of Qi is relatively large, about several million, and Linzi is a relatively large city among the seven countries at that time. Secondly, it may be Zhao, with a population of several million. The battle of Changping killed more than 400,000 Zhao troops. The population of Chu is also more than several million, and the population of Qin is certainly more than several million. At the end of the Warring States period, the population of Xianyang reached one million. Other countries, such as Yan, are remote and sparsely populated. Korea and Wei are small in area and population.

Second, the area of the seven countries is more complicated, because during the Warring States period, wars continued and the area of each country was uncertain. Take Chu as an example. At the beginning, Chu controlled the Jiangling area in Hubei today. After hundreds of years of development, it has reached the East China Sea, Zhongshu in the west, Nanling in the south and Huaihai River Basin in the north, with a total area of about 2 million square kilometers. But soon, Chu was defeated by Qin, Zhong Shu and Jianghan were separated by Qin, and the king of Chu retreated to Shouxian County, Anhui Province today. So later in the Han Dynasty, Xuzhou was the capital of Chu. Therefore, during the Warring States period, the area of the country was not fixed, and it was different every year, big and small.

Specifically, at the end of the Warring States Period, the territory of the State of Qin started from Lintao, Gansu in the west, reached Hanguguan in the east, reached Qin Changcheng in the north, Sichuan Basin in the southwest and Jianghan Plain in the southeast, with a total area of about1500,000 square kilometers. After cutting the territory of Chu, it expanded to about 2.5 million square kilometers. As the State of Chu said earlier, Jiangsu, Anhui and Jiangxi provinces are less than 500,000 square kilometers after cutting off a large area of land. Qi, east to the sea, north to the ancient Yellow River, south to Lu (after Lu was destroyed by Chu, the southern part of Qi was Chu), and west to Wei, covering an area of about 200,000 square kilometers. Zhao, most of Hebei province, is in the south-central part of Shanxi, covering an area of about 200,000 square kilometers. Yan, east to Liaodong, west and north to Yanshan and south to Zhao, covers an area of more than 200,000 square kilometers. Wei is located in central Henan and southern Hebei, with an area of about100000 square kilometers. South Korea, Zhengzhou, Xinzheng and surrounding areas in Henan Province, covers an area of less than100000 square kilometers. Something like that If the State of Jin is not divided by Zhao, Wei and Han, then the State of Jin is also a big country with an area of at least 500,000 square kilometers. At its peak, it is said that most parts of Shanxi and Hebei reach Yanmenguan in the north, Yellow River valley in the south, central and eastern Hebei in the east, Qi in the southeast and Yan in the northeast. The west faces Qin across the Yellow River. Hanguguan belonged to the state of Jin at that time, and the east of Yishan was the sphere of influence of the state of Jin.

As for Wu, Yue, Zheng, Lu and Wei, it is even more difficult to say that Wu is probably in today's Jiangsu and Zhejiang provinces. Because Wu Sheng was extremely prosperous and died soon, it is impossible to determine its specific territory. Not to mention the state of Yue, even the year when it was destroyed by Chu is still controversial. In the early days of Zheng Guo's rule, the area was relatively large, probably in today's central Henan, Xinzheng and Zhengzhou, and was later divided by the Jin and Qin powers. Lu has been in Yanzhou and Qufu, Shandong Province, and was divided by Qi and Chu. Weiguo is smaller. At first, it was said that most of today's eastern Henan was later carved up. That's it. Can't be more specific. Moreover, Sima Qian's historical records of the territories of various countries are also relatively brief. Later, there were geographical records in the Han Dynasty, but they were all recorded in the Han Dynasty.