So I was reading how China + India accounted for almost half the worlds population as well as production during/before the Middle ages. Even in technology (upto before industrialization) they were more or less at par with Europe.
Then why did they always lose to western invaders first to the middle Eastern (Islamic) invaders and later to European invaders?
Not only did they fall but it seems they didn't even put much of a fight.
(I'm sorry if I'm wrong at any point, I'm not very educated in this topic)
Since you listed Japan in your topic line, I'll say shortly that Japan certainly didn't fall. The only Western invaders to ever occupy Japan were Americans at the end of WWII. Japan was shaken by Western threats in the mid 19th century, and forced to accept unequal treaties but they were never invaded and very quickly industrialized, becoming one of the last big colonial powers.
I hope you get answers for other Asian countries.
To add to the brief answer of /u/NientedeNada, I would like to mention that China did not fall, either. When we talk about European invasions of China, we tend to think of the Opium Wars or the Boxer Rebellion. What we tend to forget is how utterly tiny these invasions were. Up until the early 1920s, when the National Humiliation narrative became linked with the conflict, there was not even a Chinese name for the First Opium War, which was merely 'a "quarrel", a "provocation" or a "disturbance"'.^1 You're less wrong, however, in suggesting that, in the 19th Century, Chinese armies were consistently defeated by 'Western' foes – by which I presume you mean the Europeans rather than the Khanates of Central Asia, whose persistence was rarely rewarded with lasting victory. Three main factors emerge in explaining this: internal divisions, technological inferiority, and limited scale of conflict.
The First Opium War is probably the best illustration of this. The Nemesis, an iron-hulled 6-gun steamer (although not technically an ironclad – Nemesis had a thin iron hull rather than purpose-built armour plating), devastated Chinese fleets on numerous occasions, and British naval gunnery from conventional vessels was advanced enough that they more than outranged Chinese shore batteries.^2 Mobile artillery pieces and percussion cap muskets gave the British a decisive advantage in close quarters fighting in Zhenjiang and Ningbo.^3 Most battles consisted solely of a preparatory bombardment followed by an amphibious landing.^4 However, we should not forget that the Chinese people were massively divided, as well. Cantonese militias attacked Hunanese regulars for alleged eating of babies,^5 whilst officials in Zhenjiang terrorised the people before the British arrived, and many alleged that pro-British fifth columnists had emerged as a result.^6 The Qing leadership had long denigrated its Han subjects,^7 and as early as 1793 some British observers predicted that the Manchu leadership was likely to be overthrown in a nationalistic revolution – although their time estimate would be off significantly, at least as far as a successful overthrow was concerned.^8 However, the First Opium War ended with quite a limited deal for Britain – merely the opening of four treaty ports along the Chinese coast. There was no grand imperial conquest (the small concession areas in the treaty ports would be subdivided between multiple countries). The problem was that Britain could only ever win within gunshot of the sea. As soon as the naval artillery was gone and the British ground forces entered the interior, there was a genuine risk of being overwhelmed. The First Opium War could only ever have been a very limited war fought for very limited aims.
When it came to the Second Opium War, it is again easy to forget that, apart from the Europeans' Minié rifles and steel artillery, the invaders had the advantage of exploiting a time of crisis. The Taiping Civil War and Nian Rebellion sapped immense amounts of resources, with nearly 150,000 Qing troops were lost with the destruction of the Second Jiangnan Siege Camp by Li Xiucheng's forces in 1860, for example. As a result, there were very few men left to defend other theatres – a mere 60,000 held the crossing at Palikao (Baliqiao) against the Anglo-French troops near Beijing in 1860, who were easily routed by superior firepower from the 10,000 Europeans opposing them (assisted greatly by their newly-introduced Armstrong breech-loading cannon).^9 In contrast with continental European wars like the recently-concluded Franco-Austrian War of 1859, in which the Battle of Solferino saw nearly 300,000 men under arms, the Second Opium War was barely a blip on the radar. Once again, this was a short, swift war with relatively small aims – further trade concessions, but no real territorial damage.
Contrast these with, on the other hand, the Sino-Dutch War of 1661. Unlike the 19th-century Qing, the Ming loyalist Koxinga had with him a well-trained, united group of regular followers, including the so-called 'Iron Troops' modelled on Japanese samurai. However, technological disparity between the two sides was similarly quite severe, with Dutch fortress technology was far in advance of Koxinga's siege capability. Yet Koxinga won. Why? Aside from good troops, commitment. Koxinga aimed to conquer, had a 20:1 numerical advantage, and was willing to engage in prolonged operations against the Dutch, capturing Fort Zeelandia in a nearly year-long siege.^10 I think that this is a pretty good way of showing why the Qing were so much less successful – they were unable to concentrate the forces necessary, both moral and physical, that were necessary to overcome the technological advantages of their foes.
Ultimately, however, European wars in China were never wars of conquest. Take the Sino-French War of 1884-5, the intervention against the Taiping in 1862-4 or against the Boxers in 1900. These were never to fought actually obtain Chinese land – indeed, the Sino-French War was fought almost solely in order to secure territory in Vietnam rather than to exact concessions from China itself.^11 Western 'domination' was secured through economic spheres of influence and control of institutions like the railroad, not military conquest.^12
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