0 From 334 BC to 324 BC, the Macedonian king Alexander led his army to the east. He conquered the cities and territory, destroying the powerful Persian Empire, and fought as far as Afghanistan (Bat Klia), which is only one step away from China's Xinjiang today. However, what is puzzling is that Alexander, who was determined to conquer the world, did not march eastward and arrived in China, but directly led his troops back to Babylon.

Some online history enthusiasts believe that Alexander is afraid of China, so he did not go east. After all, at that time, the Qin State had already carried out Shang Yang's reform, and the country was prosperous and the people were strong. Unfortunately, Alexander did not know what was happening in China. Even if he knew Shang Yang's reform, he would still lead the army to the east with his character of not fearing heaven and earth.
So why didn’t Alexander dare to fight in China? To explain this, the author should first talk about the ancient Greeks and Romans' understanding of China.

It is said that the mapping of ancient Greece originated in the 6th century BC, and the philosopher Anaximand is considered to be the first Greek to draw a map. At that time, the Greeks knew nothing about China and thought that the easternmost country in the world was India. In the 5th century BC, Chinese silk had been sold to the Athenian city-state, but the Greeks who claimed to be knowledgeable still did not know where China was.
It was not until after Alexander's expedition, that is, in the mid-2nd century BC, that Greeks living in Central and West Asia learned that there was another country in eastern India. The Greeks did not know the specific situation of this country, the only thing they knew was that this country produces silk. Therefore, the Greeks named this Eastern country "Ceris", which means "the country of silk".

By the Roman period, many Roman scholars mentioned "Ceris", and in the poems of Horace, Virgil, Ovid and others, Ceris was mentioned. However, their perception of Cyris is ridiculous. For example, Horas once believed that the Cyris lived somewhere in India, with a hot climate and a rich tree with fluff, and silk was woven from these fluffs.
In the eyes of the ancient Roman naturalist Pliny (23-79 AD), Cyrius was tall, two meters tall, red hair and blue eyes, and a slutty and harsh voice, and could live to the age of 140. At the same time, the Cyris are born to love peace and do not like attacks and are extremely fair in doing business.

It is obvious that both the ancient Greeks and the ancient Romans have extremely wrong understanding of China. And this error is also reflected in the map they draw. Crodis Ptolemy, a famous geographer, was born in 90 AD and died in 148 AD. He is a Greek born in Alexandria, Egypt.
This man has been knowledgeable since childhood, and has collected the great achievements of ancient Greek geography. He once wrote the book "Geography". In this book, Ptolemy drew the first world map in human history. Judging from the level at that time, this map already had the prototype of a modern map. On the map, the mainland is composed of Europe, Asia and Libya (Africa). The world ocean only sees the West. The map distinguishes two major inland seas: the Mediterranean Sea and the Indian Ocean. However, looking eastward from India, the position that originally belonged to China was blank. At that time, China was still in the Han Dynasty, and the Romans knew nothing about the Han Dynasty.

Ptolemy map, from the east, it is indeed not drawn in China. Because it is not valued by the world, Ptolemy's geography has gradually been lost. However, after the establishment of the Arab Empire, Arab scholars with strong curiosity began to collect large quantities of ancient Greek and Roman literature, turning on the "Great Translation Movement", and the "Geography", which had been lost for hundreds of years, was also rediscovered. Recently, an Arabic copy of Geography from the 12th century was discovered in Syria. In the manuscript, Ptolemy's world map is fully reproduced, and we modern people can finally see the true appearance.
It is obvious that from ancient Greece to ancient Rome, Europeans knew nothing about the specific situation of China. Ptolemy in the 2nd century AD did not know about China's existence, and Alexander, who lived more than 500 years ago, didn't know about it. Alexander once determined to conquer the known world, but China is an unknown world.Whether in terms of conditions or motivation, Alexander could not conquer China, and he didn't even know that China existed.

Compared with the Greek and Romans, the Han people at that time had a very clear understanding of Europe. Among the Han people, Rome was called the "Qin Qin" because the Romans "grown up and have a fair and similarity to China." At that time, the Romans did have black hair and black eyes, a medium figure, which was somewhat similar to the Chinese. In addition, "Book of Han: Western Regions" also describes Rome:
"There are thousands of miles of land, and there are more than 400 cities. There are dozens of people in small countries. Stones are used as cities and villages. Post pavilions are all covered with chalks. There are pine, cypress, trees and grass. The kings have no ordinary people, and they are all simple and wise. The country is full of disasters and storms, and they are often abandoned and reincarnated. Those who are released are willing to be demoted without complaints."

It is obvious that the Han people not only knew that Rome was a big country, but even the democracy of the country was heard of. Compared with the Qing Dynasty, who did not know whether "Russia has land access to Britain", the Han people more than 2,000 years ago were truly open to the world.
In short, the reason why Alexander did not expedition to China was entirely due to cognitive restrictions, and they did not know that China existed. But if the Macedonians really attacked China, the author would not be optimistic about their fate. After all, the Qin army was not a vegetarian.