EDIT: Alexander would have also fought the Chinese during the Warring States period, not the Qin Dynasty.
Yup and about the same time the Art of War was being formulated.
The crossbow started appearing around the latter half of the Warring States period. As for cutting off supply lines. maybe you need to read a bit more what they do, yes, in the Art of War. Even in this period, there is already the use of what Liddel Hart would call "Grand Strategy", in which there is the total concept of war that involves State, Economy, People as a collective entity; about the use of politics and high level strategems; psychological warfare; the concept of morale; the concept of logistics___especially logistics---to boost your own and cutting off your opponent.
In addition the Chinese already do have the numbers. Some of the Warring States are able to field armies as much as 500,000 men. Some of the States like the Wu Kingdom (subject of the Art of War), has well developed navies, and was practicing the concept of amphibious assault.
At the start of the Warring States, the northern states like the Chou, essentially followed a Middle Eastern style of warfare---chariots and all---indicating perhaps some influence from Middle Eastern empires. The Chinese pronounciation for "car" is the same as the one they used for chariot and other wheel drawn carriages, and yet sounds similiar indeed to the first syllable of the word "chariot". At the end of the period, when the Qin has conquered everything, Chinese warfare is much more closer to the European medieval style of warfare. In fact, all the warfare technologies attributed to the Qin---which never last for two generations---and the Han, was born from the Warring States period. At the end of the period, there were professional standing armies with infantry wearing chain, linked or scaled armor, much like medieval Europeans. This sort of armor gives much more flexibility, strength for lightness, comfort and body ventilation than the plated armor used by the Romans.
Alexander would have fought them probably between 321-315 BC. I'd like to point out Alexander had a reputation of being a a genius general. This would have hurt Chinese morale if they knew.
It would be a surprise for Alexander to meet someone like Sun Tzu or whatever his real name was. Might be too late for Alexander to meet someone like Qin Shi Huang Di aka Zheng, as Zheng was just a generation apart.
You can't have a million man standing army when it comes to the Chinese, because they have a lot of people to feed! They, like Rome, had an agricultural based society.
So was Alexander's empire and every empire on Earth at that time. Mind you, the Chinese was probably well ahead in terms of social and agricultural engineering too (e.g. artificial irrigation).
They couldn't afford to have giant standing armies because they would have to be able to feed them and pay them as well as have enough food production to feed the people. So, their army was mainly conscripts. Conscripts are inexperienced and wouldn't stand well to Alexander's battle hardened troops, especially if he used his Phalanx's effectively and incorporated his Javelin/Phalanx combo. He had other kinds of infantry, although his army was mostly phalanx infantry. (He had mercenaries and recruited Thracians.)
Alexander faced what was basically a conscript army in India and eventually he lost. Much of Alexander's battle hardened troops have been attritioned. Morale gets lower and lower the farther they are longer from Greece. Battle hardened? More like Battle fatigued. More and more he was relying on Persians, Babylonians, and other indigenous peoples among his ranks.
During the Warring States period, the Chinese---which don't formally exist then---had been extremely battle hardened on their own after the long wars. This is not a civil war because the various peoples within China lacked a national identity and consciousness then. They viewed each other much like Europeans do within their continent---your English, French, Germans, Italians and Spanish, are much like the Yen, Zhao, Shu, Qin, Wu, Han, Song, etc,. They even have seperated languages, writings and customs, which were only formalized and rationalized under a single system under the unity of the Qin rule.
Phalanx is worthless on irregular ground, as the Romans later discovered. And Alexander was abandoning the Phalanx the more he got deeper into Asia. Turns out that light infantry could go inside the gaps in irregular ground, and with small short, and straight double edged swords, do much better infighting than the soldiers within the Phalanx holding their spears.
But this is exactly the kind of troops the Warring States of Wu, Shu, Qin, and Yuet happen to have. In addition to that, the use of light shock troops would play havoc on anyone's supply lines, logisitics and morale---tactics documented in the Art of War and historically in the Warring States period. Call it proto-guerilla warfare.
Furthermore, the Chinese already had the concept of
squads by that time period.
From Ralph D. Sawyer, a historian on this topic from his book Nature of Warfare in China.
Until the advent of hot weapons and their gradual, often blundering adoption by the
world’s armies, China’s military science was, as in many other areas, whether for
better or worse, virtually light years ahead of western practices. When the Greeks
were struggling to escape the confining nature of the phalanx and its single tactic of
the mass collision, China had already perfected numerous formations and methods
of deployment, as well as an underlying hierarchical organization based upon the
squad of five that, when coupled with precise training methods, allowed articulation,
segmentation, and the execution of both orthodox and unorthodox tactics.
----
They didn't have the cross bow, so they can't even use that against Alexander. Alexander would have cleaned house against the Chinese. Chinese cavalry isn't as great as everyone thinks. I'd also like to point out that the Chinese couldn't have had steel until around 300 BC at the earliest, so they don't have that. Steel is expensive and time consuming to make anyway, so it would be rather hard to equip a large army with steel weaponry.
Not true. Crossbows was developed in the Warring States period.
Chinese military was conscript based actually. It's impossible to have a gigantic standing army and have such a large population to feed, as well as the army. (And paying them.) Their cavalry was in fact, not similar to Hunnish cavalry, but basically WAS Hunnish cavalry. (They got Cavalry in the Warring States Period from the North.)
Not true. Hunnish style cavalry only appeared in the Han Dynasty. The Northern States were also using chariots, and their cavalry is closer to the Middle Eastern style. The warring States to the South were mainly infantry.
To be honest with you, I don't think Alexander would win against King Zheng of the Qin, aka Qin Shin Huang Di. Alexander for all his military genius, does not have the total society-war concept of Zheng and the latter's ability to perform radical social engineering to transform his entire kingdom into a total war machine, and then applied similar concepts to all his conquered territories. He was the first totalitarian ruler in history, when the concept of totalitarianism never appeared until the 20th Century. The result of this revolutionary social engineering, eventually became the unified country of China. The Qin army would be something like the original Spartans, with much greater numbers and with superior technology. Conscript army? Hardly, his army was like a well oiled military machine, highly disciplined and ruthless, and for that reason, he kicked literal butt with everything he came acorss.
By the way, saying that because an army has been around longer means it's better trained is wrong. In fact, it's more likely it's worse trained if it doesn't innovate regularly, and unlike the Romans, the Chinese only fought themselves, so war was basically the same thing. They didn't innovate as much, because they rarely fought anything new. The Romans fought a variety of cultures, so their army probably was more flexible than the Chinese.
Complete nonsense. Not only was the Chinese not unified among themselves and lacked true national identity; they also fought proto Mongolic, proto-Turkic, proto-Tibetan, proto-Tungusic/Korean, proto-Viet/Khmer/Thai/Malay. not to mention Caucasoid peoples like the ancestors of Tocharians. That is an awesome variety of opponents ranging from steepe northern horsemen to jungle warfare and even fanatic holy wars and their style of brutal, total warfare. And yes, there was quite a number of Caucasian peoples within China who would eventually mix with the population but still leave their genetic heritage embedded with every Chinese's DNA.
The Qin succeeded in something any single European ruler never managed---to conquer everyone in their path. then exercise a grand social experiment that literally united all these diverse peoples into a single national consciousness.