He's not wrong in saying later Chinese walls became stronger - prior to the Mongol invasion of China, Chinese city walls were built mostly out of rammed earth. During the Siege of Xiangyang, the Mongols brought in Muslim engineers who built them counterweight trebuchets that completely levelled a portion of Fancheng's wall. This, combined with the rise in gunpowder, led the Chinese to build stronger walls.

Now, regarding his theory on Chinese walls. Well...there is a reason why it's called a theory and not a fact. The big authority on this is Joseph Needham, and according to his book Science and Civilisation in China, the Chinese did indeed invent big cannons.

Volume 5, Part 7, Pages 336-337

Among the large firearms there is none that is greater than the 'great general gun'. Its barrel (used to) weigh 150 catties, and was attached to a stand made of bronze weighing 1000 catties. It looked rather like the fo-lang-chi cannon. Yeh Meng-Hsiung changed the weight of the gun to 250 catties and doubled its length to 6 feet, but eliminated the stand, and now it is placed on a carriage with wheels. When fired it has a range of 800 paces. A large lead shell weighing 7 catties is called a 'grandfather shell' (kung) and the next shell of the medium size weighing 3 catties is a 'son shell' (tzu), while a smaller shell weighing 1 catty is a 'grandson shell' (sun). There are also 200 small bullets each weighing 0.3 to 0.2 oz (contained in the same shell) and called 'grandchildren bullets' (chhun sun), while the saying is that the 'grandfather' leads the way and the 'grandchildren follow' (kung ling sun shang). They are supplemented with iron and porcelain fragments previously boiled in cantharides beetle (pan mao) poison. The total weight of the projectile is some 20 catties. A single shot has the power of a thunderbolt, causing several hundred casualties among men and horses. If thousands, or tens of thousands, of (this weapon) were placed in position along the frontiers, and every one of them manned by soldiers well trained to use them, then (we should be) invincible. This weapon is indeed the ultimate among all firearms. At first its heavy weight caused some doubt as to whether or not it was too cumbersome; but if its transported on its carriage then it is suitable, irrespective of height, distance or difficulty of terrain.

A catty is about ~500 grams.

It's also worth noting that cannons really began to be developed during the Ming and Qing. The primary concern of both dynasties was frontier enemies who did not possess walled cities - for the Ming it was the Mongols and later the Manchus and for the Qing it was the Dzungars, and so the development of artillery typically mirrored their needs. Smaller artillery was easier to transport and was able to be mass manufactured, indeed I commented on the superiority of early Qing cannons compared to Europeans ones here.

Regarding his comment on city walls, I cannot say for certain. I looked at Needham and he did not compare them to Europe.

/u/CK2benchmarks

In case you haven't yet, and for the benefit of other readers, please do read through some of the great comments brought up by /u/hbborgg on this thread where you asked "How was gunpowder used in China and why didn't they invent guns instead of Europeans?"

I have read Andrade's earlier book Lost Colony: The Untold Story of Europe’s First War with China (Princeton, 2011), and his recent paper An accelerating divergence? The revisionist model of the world history and the question of eurasian military parity: data from East Asia, Canadian Journal of Sociology, 36 (2), 2011.

Chinese Guns and Cannons

When it comes to the narrow question of Chinese cannons and walls, I agree with /u/lordtiandao that Andrade has an interesting hypothesis, with some discoveries that support his theory. However, as I said in another thread, to argue about "who has what" e.g., the Chinese had strong walls made from rammed earth, other historians instead focus on "what were the challenges and what resources were available." In this I think two books are must reads: Chase's Firearms: a Global History and Swope's The Military Collapse of China's Ming Dynasty, 1618-44.

Chase states the need to examine the challenges that the Ming faced: In the period between Yongle's rule to the end of the Ming dynasty, there were three areas of force projection: Mongolia, Vietnam, and the Southern Seas. In all three areas gunpowder weapons were not key, if anything else many have criticized their suitability. In Mongolia, gunpowder weapons burdened the troops, suffering through a long baggage train and lack of mobility as infantry; in Vietnam they faced guerilla warfare; in the South Seas they lacked a strong adversary and as we know these expeditions were an anomaly for the agrarian Ming. This is what leads to Chase's key thesis on China in 1500s: that its military policy was one of defense. At the same time, it is not correct that (Imperial) China lacked challenges, given the three areas of force projection. Hence, the need to look at the type of challenges.

A Question of Scoping

When Andrade writes on the Sino-Dutch war, he is widely applauded for his critical analysis in that narrow context. However, in his paper he extrapolates his analysis on the larger context of China. Here problems start to appear and I will try to enumerate some of the issues with this approach.

1. Scale and power projection. Europeans powers were fighting these battles halfway around the globe, so they were always very few in numbers (a few hundreds up to 1,200 on the Dutch side on Formosa, at least thousands on the Ming side).

2. Special access to personnel and technology. Andrade makes a big deal out of the reported accuracy of Chinese snipers shooting back at the fort. However, given Koxinga's background and nature of power, he had access to some unique groups of soldiers, including musketeers from Korea (or possibly Japan) who were well-drilled in what appeared to be western ways of conducting infantry warfare. But it is difficult to analyze how widely available such quality troops are. Swope's book goes to a long way to show that troop quality had very high variance.

3. Parity and exchange. In his paper Andrade claims that exchange was two-way, between Europeans and Asians. This is highly debated, even as we go beyond the 1600s.

4. Question on divergence. In his paper Andrade gives a very nice summary of historiography. However I think this deserves its own discussion which I will summarize in the next section.

Divergence: initial conditions and evolution

There are two key questions here: 1) Was there a divergence when Europe first came to China, and 2) How did this divergence evolve over time. In both questions, an accepted fixed point is China's eventual loss in the Opium Wars.

The answer to the first is evolving. Early Europe-centric historians tended to paint China (and Asia more generally) as always being backwards compared to the Europeans.

When the Portuguese came to China in the 1540s (through Macao and Guangzhou), they found that China already knew how to cast iron and bronze cannons. But the Chinese were very interested in the [Portuguese] methods for building ships, casting guns, and making gunpowder. This hints the Chinese felt the Portuguese knew something about gunpowder they didn't. The earliest Chinese writing that mentions corning is from 1560, in a series of writings by general Qi Jiguang. Chase then deduces corned powder was likely introduced to China by the Portuguese.

Swope and Di Cosmo say that the diffusion of firearms in Asia cannot be understood as the linear outcome of increased European mobility, and more strongly that through examples showed that China was not a monolithic entity. Meaning that development and access to weapons, military ideas, and so on differ greatly depending on which part of China you are talking about.

Further in this period, there was a lot of diffusion of knowledge, so it becomes difficult to trace when a specific item was introduced or invented or if it was legacy knowledge. For example, when the Portuguese encountered the Japanese in Tanegashima in 1543, the locals thought of the matchlock as novel, thus historians tend to think that the matchlock was introduced by Europeans to east Asia. Unfortunately, there is lack of discussion of firing mechanisms, which /u/hbborgg and I find to be very disappointing. Di Cosmo goes to say that folangji the Chinese term that used to be understood as "Frankish machine" may be the sinicized version of "farangi", thus suggesting that some culverins made their way not from the Portuguese but from the Ottomans. So the issue of figuring out what came from where is indeed very complicated.

The Portuguese mentioned gunpowder weapons in India when they first arrived, although as far as I know it's not clear what exactly they are. Some are mentioned as rockets, some as guns. But Chase mentions a painting from the 1460s that show a cannon, so he deduces the Indians already knew of gunpowder weapons by that point. When the Portuguese took Malacca in 1511, they mentioned they confiscated "thousands of guns" but no mention of their exact nature nor quality. They could have come from the Ottomans or the Safavids. Everbody seems to have had low opinion of India-made guns, Chase quoting comments from European explorers at that time that Indian furnaces did not run at sufficiently high temperatures, thus limiting quality of casting.

And now the answer to the second part: Revisionists in the 1990s argue that in the earlier parts, there was little gap in power, however a divergence started much later in the late 1700s due to the Industrial Revolution in Europe. Recently some scholars have argued against this, in the so-called counter-revisionist school.

On sources

I'd love to get /u/lordtiandao 's take on the Mandarin page of 火龍神器陣法, which say

据后人考证，发现书中一些细节有误，如称朱棣为“成祖”（庙号）等，但因元朝忽必烈攻打日本时已经使用铁火炮、朱元璋大战陈友諒于鄱阳湖时也早已使用火箭、火銃、火蒺藜、大小火枪等多种火铳[1]，尚能断定今本《火龙经》可能经过嘉靖年间修订而成，但其余书中原文應不该置疑。

With my poor command of Mandarin, I understood to say that parts of Huolonjing was edited and/or amended during the Jiajing era. Is this correct? What is known about the origins of the Huolonjing as we have it today?