Not to get off topic but Napoleon was awesome until his army encountered the RUSSIAN WINTER and the combined opposing armies of Europe, be they British, German or Russian were outmatched until the Russian Winter killed off more troops in a few months then then Napoleon's army normally lost in years worth of hard fighting.
Then lest we think the Russian Winter was just a fluke Adolf Hitler pretty played Napoleon's part over again doing well until his army moved into conditions far colder then any German army had ever operated in.
Russia has 2 great generals in history, general January and general February. Conquering Russia means starting in the spring and ending before fall. The Russians themselves deserve some credit of course, but its probable they could not have withstood more elite forces without the intervention of some of the cruelest seasonal weather to be found anywhere on Earth.
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As for weather however I do wonder how bad the weather would be to Alexanders army in its most likely entry point into Chinese territory (The extreme southwest) I am not familiar with the lay of the land in that area but I suppose it could be miles and miles of barren grassland requiring long long supply lines, until the Alexandrian army could begin foraging Chinese farmland.
Anybody have any idea what the environmental conditions would have been like along Alexanders most likely (theoretical) paths of invasion of the Qin?
going in from southwest, from india, he'll have to climb some of the highest mountains in the world, and travel across the tibet plateau...which means a huge chunk of his men wont make it and/or they get lost and starve to death,even if the army does survive there will be no logistics available for them. going in from afghanistan means they'll have to walk through the desert of Xinjiang and then Qinghai, which means a huge chunk of his men wont make it and/or they get lost and starve to death,even if the army does survive there will be no logistics available for them. even if they get through those they'll be fighting in Sichuan, which means they'll be fighting in mountains, alexander's phalanx and calvary will be useless...on top of that he is fighting against roughly a million men. the only good thing about this is that if he makes it through all those terrains, he is pretty close to Qin capital because back then Qin capital is in what is now Xi An. which is pretty close to those moutain areas in Sichuan. so if i knew China and i was alexander's advisor i'll likely recommend against invading China...though he'll prolly cut my head off and the western historians later on will describe me as a coward...so actually i'll not tell him everything and laugh when his army gets owned lol.