If Alexandar had gone to China, he would have been defeated easily by the Chin state. Chin state that located in Western China and united the Chinese world in 221 BC would have probably been the first state he would have encountered.
Not only was China much larger, more powerful than Persia, it was also more technologically advanced than the West (The Chinese considered Persia the West as well as barbaric) along with well organized military training and tactics. Iron was already replaced by steel during this time in China.
During the warring state period of China, each major state could easily deploy an army of 200,000 +. The Chin state also once deployed a pofessional and well trained army of 500,000 against the Zhao. Sun Zhi's Art of War was widely studied and used during that time.
The following is some of the Chinese military formation and weaponary:
Sun Bing's military manual written in 340 b.c. and unearthed in 1972 shows a number of deployments.
Here are some described:
The Wu Îé - five-man squad in line astern.
The Dui ¶Ó - 10 Wu in line abreast (5 men deep and 10 across) 50 men
The Bo ²® - Two Dui in line abreast (5 men deep and 20 across) or line astern (a square 10 men deep and 10 across) 100 men
The Qu Çú - Two Bo in line abreast (5 men deep and 40 across) or line astern (20 men deep and 10 across) 200 men
The Square ·½Õó - made up of several rows of Qu, with the HQ in the middle of the rear row. Not necessarily a true square, can be rectangular. A favourite tactic was to place stronger Qu on the flanks, and then lure the enemy to attack the centre and be outflanked.
The Circle Ô²Õó - a Qu reformed into a ring, with the HQ protected within it. A highly defensive formation.
Dispersed Formation ÊèÕó - increasing the distance between individual Qu in a square, so as to mislead the enemy or divide his forces.
Close Formation ÊýÕó - decreasing the distance between individual Qu in a square, for strength in close-quarter fighting.
The Awl ׶(zhui)ÐÐÖ®Õó - A wedge (triangle with one point facing forward), a highly offensive formation. Also known in later history as the Male Formation êò(pin)Õó (you'll see why later).
The Wild-Goose-Flight Formation Ñã(yan)ÐÐÖ®Õó - A V-formation with two wings for enveloping the enemy and the HQ in the middle. Or an inverted-V for a defensive formation that can quickly be converted to offensive wedge. The V-formation can also be modified into a flattened U known as the Basket Formation »þ(ji)ÐÎÕó or Female Formation ĵ(mu)Õó, for luring enemy wedges into the centre and then enveloping them.
The Hook Formation ¹³ÐÐÖ®Õó - A line abreast with the two ends sloping inwards to avoid being flanked. Probably most suitable for archers or crossbowmen.
Then there are unorthodox formations such as the Bagua which is a highly flexible formation with high degree of manuvre.
China had a more advanced technology.
By no later than the end of the Spring and Autumn Period (770-476 B.C.), the Chinese developed the technology of the blast furnace. This allowed them to heat the ore above its melting point, and produce cast iron. Among the inventions that made this possible, was the double-action bellows. The manufacture of iron, using a blast furnace to produce a molten metal, greatly expanded production: The process could be continuous, as the molten metal flowed from the reducing furnace, was poured into molds, and made into a large variety of products.
The blast furnace was introduced in Europe, on a wide scale, only in the late 14th Century, almost 2,000 years later. The use of cast iron was, unfortunately, introduced in Europe largely for the production of cannon; Henry VII constructed the first blast furnaces in England. The replacement of the bloom furnace with the blast furnace, increased productivity in the English iron industry 15-fold.
The Chinese were able to manufacture superior tools, that the more primitive European metallurgy was incapable of producing, which led to a substantial advance in productivity throughout the entire economy. As early as the Third Century B.C., the state of Qin appointed government officials to supervise the iron industry, and penalize manufacturers who produced substandard products. The Han Dynasty nationalized all cast-iron manufacture in 119 B.C. Around that time, there were 46 imperial Iron Casting Bureaus throughout the country, with government officials insuring that cast-iron tools were widely available. This included cast-iron plowshares, iron hoes, iron knives, axes, chisels, saws and awls, cast-iron pots, and even toys.
The Chinese also developed methods for the manufacture of steel that were only matched in the West, in the recent period. The characteristics of iron alloys are related to the carbon content. Cast iron generally has a high carbon content, which makes it strong, but brittle. Steel, which is an alloy of iron with a low carbon content, is strong and more durable. The use of steel in agricultural implements was introduced, on a wide scale, during the Tang Dynasty (618-907 A.D.). This led to a further improvement in productivity.
In the Second Century B.C., the Chinese developed what became known in the West as the Bessemer process. They developed a method for converting cast iron into steel, by blowing air on the molten metal, which reduced the carbon content. In 1845, William Kelly brought four Chinese steel experts to Kentucky, and learned this method from them, for which he received an American patent. However, he went bankrupt, and his claims were made over to the German, Bessemer, who had also developed a similar process.
The Chinese also had superior weapons and tools:
Pilum is a primitive weapon for limitd throwing power. With the presense of crossbow, their is noneed for weapons of inferior power. As for pavises, the warring state shield industry was highly advanced, the shields are made in fine hide along with maximu care, the rules were stric, if rat bitten marks were found, the shield carers are severely punished. Shields are made through careful calculation of the time in drying the wood and hide to maximize defense power. And designed in such shape to deflect missiles.
Sun Zhi lived in 5th century BC during the Spring and Autumn peiord (2 hundred years before Alexander) but his war mannual was widely studied during warring state period of China.
id kinda like to know where to download the scenario? 
