From a bigger global perspective, the era of Tang Dynasty (618 to 907 C.E.) was China’s most crucial period. While other periods like the Yuan (1271 to 1368 C.E.) and Qing (1644 to 1912 C.E.) eras possessed larger territories, these were mostly barren wastelands. An aspect that should be considered is that whether the areas of territorial control had any global strategic value. The Tang period in this case possessed territorial range of great strategic significance, as its territories and spheres of influence covered today’s most strategically important regions like Japan, Korea, Vietnam, Afghanistan, Russia, and Central Asia. During its peak on the 7th century, almost all major Central Asian oases were controlled by the Tang, and its territories extended from Ha Tinh of today’s Vietnam in the South, Angara River region of Russia in the North, Bukhara of Uzbekistan in the West, and Tonghua of China’s Jilin province in the East.

As a country located in the heart of Asia, Afghanistan is linked to China and East Asia in the East, ex-Soviet Union controlled region in the North, South Asia in the South, and the oil-producing Middle-Eastern region in the West. In modern history, the world's major powers understand the extremely important strategic position of Afghanistan, in terms of its geographically significance and oil resources. For this reason, Afghanistan was frequently invaded. The British for instance, attempted three invasions. When Afghanistan finally gained its independence from the British Empire, since then the Empire was in the state of decline. In 1989, the Soviet Army withdrew from Afghanistan, and two years later the Soviet Union dissolved. Today, in the tragic Afghan war, the United States spent 20 years in the country, with more than 2,000 lives killed, and more than 20,000 wounded, with more than 10 billion dollars pouring in.

The Tang Dynasty was one of the most powerful dynasties of China, and one with global vision. Hence, Afghanistan’s strategic position in the Silk Road was extremely crucial to China. The north of Afghanistan were the nomadic pastoral people like the Turks, the south were Indian polities, and the west were roads leading towards Persia and Arabia. After the Tang conquered the Western Turks in 659 C.E., as the Turkic king of Tokharistan became its vassal, Afghanistan was integrated as part of the territory of the Tang China.

To achieve effective rule and management of the Afghan region, the Tang adopted various effective governance measures and established seven administrative units known as Duhufus, or Frontier Commands. These Duhufus were located at the North, the South, the Northwest, the Bamiyan region, the Northeast towards Vakhsh river region of Tajikistan, as well as at the area north of today’s Kabul, in addition to one located at the east of Persia and within the Afghan territory.

The Tang Dynasty paid great attention to the western part of China outside the core area. The establishment of military bases in that region, with Anxi Duhufu (literally, “Area Command of the Pacified West”) as its network center, was to maintain the security of the Silk Road. This was also to ensure that China's influence could be projected to the valuable strategic regions and achieve effective control.

However, the Tang Dynasty lost its control of the Afghan region after its defeat in the Battle of Talas against the Abbasid Caliphate in 751 C.E. The loss of Afghanistan meant that Tang China lost its dominant influence, which led to the encroachment and invasion of external forces. Afterwards, An Lushan Rebellion broke out in the mid of the 8th century, and the Tang Dynasty was unable to restore its control of the Afghan region ever since. With the Abbasid Caliphate expanding its influence in Central Asia, the region gradually became Islamized.

The Battle of Talas has extremely important significance in the history of West Asia and China. If Tang China won the battle, it could become a major power that had profound influence on Europe like the Ottoman Empire, and its territory may include today’s India and the Arabian Peninsula. Of course, there is no “if” in history. History is a social experiment, and the results of this experiment have had a huge impact. In any case, the Tang Dynasty, one of China's greatest dynasties, was able to effectively rule this region of Afghanistan for nearly a hundred years, that itself is a historical phenomenon worth further studying.

Once we see history as a social experiment from geopolitical perspective and linked history of reality in our analysis of today’s Afghanistan through historical realism, we will be able to understand many problems easily. What attracts the attention of the world powers to Afghanistan today is not its minerals, gems, opium, tribes, and sects, which are only the common sense and superficial surface of Afghanistan's problems. The real significance of Afghanistan to the world's major powers lies in the fact that China's Tang Dynasty. After losing Afghanistan, China was left in a weak and struggling state for more than a thousand years afterward, reducing it from a great global empire to a country that was constantly seeking to protect itself from encroachment.

In fact, after the Tang Dynasty, several dynasties that ruled over China attempted to expand to the northernmost desert after being blocked from expanding into Afghanistan. For example, the Ming Dynasty (1368 - 1644 C.E.) briefly controlled the northernmost desert region, while the Qing Dynasty made efforts to expand to the Arctic Ocean and the Sea of Japan. However, the overall territory of China was gradually shrinking. Although the territory of the Yuan Dynasty was vast, most of it was only in name and could not be effectively governed; the core territory of the Yuan Dynasty was still the region north of the Great Wall. With the formation of this core territory, the relative brevity of the Yuan Dynasty likewise attests to the importance of Afghanistan and Central Asia to the world's continental island. Genghis Khan, the great strategist, paid great attention to the strategic position of Central Asia in the initial stage of his world conquest, and his dynasty started from the occupation of Central Asia. Therefore, from a historical perspective, Afghanistan has played an incomparable strategic role in the expansion and influence of great powers throughout the dynasties.

Perhaps it has to be pointed out that "China's version of the New Silk Road Plan", i.e. the "Belt and Road Initiative", has mentioned in its early research and formation stage that the heart of the world's continental island is Afghanistan, not the surrounding powers such as Russia, China or India. This means that whoever controls Afghanistan will have the dominant influence in the world's continental island. China, historically a traditional land power with influence and historical experience from the world's continental island, would pay a significant price as well as a high cost if it rashly commits to participate in the world competition for sea power. All these are empirical understandings formed under the historical framework, which not only integrates the humanistic experiences and imperial experiments over a long period of time, but also the result of historical realist analysis. Applying the same method to today's world, we can see that Afghanistan has become the main battlefield of the modern world powers.

The conclusion of the present and future problems in Afghanistan is simple. It is the fact that Afghanistan has always been a place where wars are waged, and where the rise and fall of world powers will be determined. From the perspective of historical realism, the withdrawal of American troops from Afghanistan today signifies not just the end of an old era, but the beginning of a new one.