I'll go through my logic and highlight the other flaws I see below, but before I do, let's bask in the wonderfully presented data set Wang and Dincecco (or their graduate students!) have given the world:
|Figure I in Yuhua Wang and Mark Dincecco, "Violent Conflict and Political Development Over the Long Run: China Versus Europe," Annual Review of Political Science (2018), vol 28, 344.|
|Figure I in Yuhua Wang and Mark Dincecco, "Violent Conflict and Political Development Over the Long Run: China Versus Europe," Annual Review of Political Science (2018), vol 28, 345.|
It is a bit fun simply to look at these maps and try and pick out patterns. (Wang has a few more maps of this type in a different working paper, where he breaks down the battles into rebellions and fights against non-Chinese foes). As Wang is a Harvard professor, my hope is that these battle locations will be added as a skin on Harvard's ChinaMap project. The applications are endless. But what do Wang and Dincecco use the data for?
I will let them explain:
Our simple model suggests that warfare may have diverse implications for political development depending on the underlying political geography context. Namely, the model predicts that political representation is more likely to emerge in the context of political fragmentation. Here, the elites may credibly threaten to move abroad if the ruler does not meet their demand for a political freedom. Furthermore, the ruler may be more vulnerable to external attack by military rivals emanating from multiple directions, enhancing the value that she places on elite loyalty. For both reasons, the elites may be in a strong enough bargaining position vis-a-vis the ruler to demand ` political representation. In the context of political centralization, by contrast, the elites’ threat to exit is less credible, due to the difficulty of moving abroad. The ruler, moreover, may place less value on elite loyalty, both because of the smaller chance that elites will move abroad and because of the greater probability that foreign attack threats will be unidirectional in nature, thereby reducing her vulnerability. The ruler’s bargaining position versus elites should thus be stronger, making the emergence of political representation less probable. With this thesis Wang and Dincecco are wading into a debate that is now about three decades old. It was kicked off when sociologist Charles Tilly advanced the claim that "states make war and war makes states."  Tilly's basic case (further developed in his book, Coercion, Capital, and European States) is that the creation and strengthening of political institutions in Europe c. 1000-1900 AD was driven by warfare. The demands of warfare drove political leaders to extract greater and greater resources from their domains. Wringing more wealth from society at large meant building political institutions capable of more vigorous wringing. Tilly hypothesized that the pre-existing shape of a given society (e.g., is its wealth held mostly in cities, in a landed aristocracy, etc.) determined the strategy political leaders would adopt when building these institutions. If you want to understand why some states had parliaments while others had czars, then you must turn your gaze back to the expedients kings resorted to in order to fund their wars centuries ago.
In the three decades since Coercion, Capital, and European States was published a cottage industry has sprung up investigating whether there really is a relationship between war and state strength on the one hand, or war and regime type on the other. The problems comes when you attempt to apply Tilly's famous framing outside the European experience. War is a constant of human history. Strong states are not. Strong states with representative institutions are even more difficult to find. If Tilly's "bellicist" model of state formation is valid, then why doesn't it work outside of Europe? For some researchers, the simple answer is that bellicist models are not valid, and some other model of state formation should be defended. Others have suggested that bellicist models are correct given certain conditions—the wars fought must reach a certain intensity, the states must not have access to external credit, they must not be divided along ethnic lines, or what-have-you, for the model to hold.
Wang and Dincecco are political economists, not historical sociologists, but their model fits neatly into this debate. What makes their case different from—and in my eyes more promising than—most of this literature is the object of their analysis. Most bellicist theories focus on aspects of the states themselves, or more rarely, aspects of the wars fought between them. The general claim is that variable Y or variable X (hopefully something that can be easily measured and thrown in a regression analysis) is what causes the different patterns of state development across the world. But in focusing in on ease of exit and vulnerability to attack from multiple directions Wang and Dincecco are shifting the object of analysis from the state to the state-system. They do not really frame it this way, of course, but this is what they are claiming: in a state system where states face geopolitical pressure on many fronts, and in which it is easy for wealthy elites to decamp to other states, war will drive leaders to compromise with local elites instead of driving leaders to coerce them. The end result of such compromise will be "representative" political institutions like parliaments and congresses.
I am strongly in favor of (and have argued strenuously for) systemic theories of state formation.  But if we are going to go down this road we must travel its full length. Imperial China and Early Modern Europe are not the only two state systems that have existed in human history. More important still, Europe is not the only state system that was full of political units that faced geopolitical pressure on many fronts and which political elites could easily exit from one kingdom to another. I have written before about how these aspects of the Early Modern European system also describe Sengoku Japan and Warring States China. I am less familiar with early-modern India, but Roberto Foa makes a very strong case in his PhD thesis that similar statements can be made about the states that emerged in the wake of the Mughal collapse.  Despite this fact, Western-style representative institutions are not to be found in post-Mughal India, Warring States China, or Sengoku Japan (the closest thing we have are the ikko-ikki leagues in Japan, but they were squashed quickly). It turns out Wang and Denecco face the same challenge that bellicists always face: how do you explain the model's failure to predict outcomes outside of Europe?
I have a few other quibbles. Was it really so easy for European elites to take their wealth with them from one state to another? More importantly, was it so hard for Chinese to escape the grasp of the state? As Wang and Denecco note, in late imperial times the Chinese state was a weak thing. The historical record is rife with tales and accounts of clans, families, and disgraced officials fleeing to the hinterlands or the borders where they knew they would be beyond the reach of imperial control. The inability of emperors to control their empire presents another puzzle. The historical consensus is that the Qin Dynasty—born out of the Europe-like geopolitical competition of the Warring States Era—was the era when state-society relations tilted strongest towards the state. Some authors have gone so far as to describe the Qin regime as "totalitarian." Never again in imperial Chinese history would the state have such strong grip on the Chinese elite.  How can Wang and Denecco's theory account for this? If their hypothesis is correct, why would Chinese in later eras have a stronger bargaining position vis-a-vis their emperor when China was a unitary state than when it was divided into warring states?
I do not have a suitable hypothesis to answer this question. To start us off, however, I do think it is helpful to consider how elite Chinese managed to subvert the emperor's will in late imperial times. One of the guiding assumptions of much comparative history and social science work on imperial China is that the Confucian bureaucracy were faithful executors of the imperial will. But nothing could be further from the truth. In imperial times, Chinese politics often devolved into high-stakes competitions between the civil service on one side and eunuchs (or in the Qing Dynasty, imperial bondsmen) on the other. Eunuchs and bondsmen were the hand of the throne. Their loyalty was to the emperor. Confucian literati, in contrast, were loyal to the dynasty. Saving the dynasty often meant doing everything they could to limit the power of the emperor. These elites self consciously described themselves as pleading the cause of the common people of China. They were not entirely wrong to make this claim. The estates of bureaucrats were scattered across the empire; unlike the emperor, they had family members in the lower economic strata, and had personal contact with farmers living in poverty. More important still (and unlike the eunuchs) bureaucrats were selected and promoted by a system that was not entirely under the emperor's control. The resulting throw-downs between the literati and the eunuchs was as dangerous as any parliamentary censure of the king. Both contests pitted the empire against the throne. What differed was the structure and philosophy of each regime's 'representative' institutions. 
Treating the Confucian bureaucracy as representative institution engaged in constant bargaining with the throne puts an interesting spin on this entire topic. If this is a valid way of framing things, and if political bargaining worked in China more or less as it did in Europe, then I would predict that potential Chinese monarchs would try to use access to the bureaucracy as a tool to win over elite support for their regimes. A cursory look at Chinese history suggests that this is exactly what happened. Conquest dynasties like the Jin and the Yuan were not considered legitimate until they recreated the bureaucratic system; one of the decisive moments in Zhu Yuanzhang's campaigns against Zhang Shicheng was his decision to hold imperial examinations. Wang and Denecco provide a similar example in their paper:
During [the Taiping Rebellion] event, the Qing government ran out of funds for its antirebel efforts. To defeat the rebels, the emperor asked local gentry for financial help. In exchange, public school quotas were adjusted in the gentry’s favor, increasing the odds that their sons would later be admitted to the imperial civil service. Wang (2017) finds that gentry located in zones nearer to the so-called Taiping Heavenly Kingdom—the revolutionary regime established by the Taiping—contributed significantly more to the emperor’s military efforts. This evidence suggests that, rather than exploit the ruler’s need for quick funds to bargain over local political freedoms, as was common in Europe, the gentry agreed to remain loyal in exchange for a greater chance for their offspring to gain entrance to the imperial civil service. Another possible way to frame this is that the gentry exploited the ruler's need for quick funds in order to increase their share of power. There was little desire to make the imperial civil service democratic, but there may have been efforts to make it more "representative."
This is a question of political philosophy—or to use the parlance of political science, it is a question of political theory. Whether Chinese conceived of the civil service system as an explicit check on the throne, whether there was a theory of representation built into the political ideals of Neoconfucian philosophy, and whether the limits of the word "representative government" are too narrow to include the imperial civil service inside them is a question for political theorists and historians to debate. The need to ask such questions at all is a reminder that the work of normative political philosophers cannot be so easily separated from more empirical analyses of human political behavior.
 Yuhua Wang and Mark Dincecco, "Violent Conflict and Political Development Over the Long Run: China Versus Europe," Annual Review of Political Science 2018, 21:341-358.
 Charles Tilly, “Reflections on the History of European State-Making,” in Formation of National States in Western Europe, ed. Charles Tilly. (Princeton, NJ: Princeton University Press, 1975), 75.
 For a few examples, Scott Abrahmson, “The Economic Origins of the Territorial State.” Mimeo (2013); Michael Niemen, “War Making and State Making in Central Africa," Africa Today, (2005) vol 53, iss 3: 21-39; Thierry Gongorra, “War Making and State Power in the Contemporary Middle East,” International Journal of Middle East Studies (1997), vol 29 iss 3: 323-340. Miguel A Centeno, “Blood and Debt: War and Taxation in Nineteenth-Century Latin America," American Journal of Sociology (1997), vol 102, iss 6:1565–605.
 For example, Keith Jaggers, “War and the Three Faces of Power: War Making and State Making In Europe and the Americas.” Comparative Political Studies (1992), vol 25, iss 1: 25-62; Anna Leadner, “Wars and the Un-Making of States: Taking Tilly Seriously in the Contemporary World,” in Contemporary Security Analysis and Copenhagen Peace Research, eds., Stefano Guzzini and Dietrich Jung. (London and New York: Routledge, 2008), 69-80; Brian Taylor and Rozana Botea, “Tilly Tally: War-Making and State-Making in the Contemporary Third World.” International Studies Review (2008) 10: 27-56;
 Tanner Greer, "Darwin and War in Ancient China, Sengoku Japan, and Early Modern Europe," Scholar's Stage (5 November 2015).
 See the working paper embedded in Ibid; Roberto Foa, "Ancient Polities, Modern States," PhD diss (Harvard: 2016), esp. ch. 3 and 5.
 For example, see Wang Wensheng, White Lotus Rebels and South China Pirates (Cambridge: Harvard University Press, 2014), 37-114.
 On the difference between Qin and later imperial practice, see Yuri Pines, Review of Zhao Dingxin, The Confucian-Legalist State: A New Theory of Chinese History. Early China 39 (2016), 311-320. The "totalitarian" title comes from Fu Zhengyuan, China's Legalists: The Earliest Totalitarians and Their Art of Ruling (Routledge: New York, 1997); for a more measured assessment of Qin authoritarianism, see Yuri Pines, Gideon Schelach, Robin Yates, and Lothan von Falkenhausen, “General Introduction: Qin History Revisted” in Birth of An Empire: The State of Qin Revisted (Berkeley: University of California Press, 2013), 1-36.
 This is one of many themes pursued in Frederick Mote, Imperial China, 900-1800 (Cambridge: Harvard University Press, 2003). Mote traces the theme throughout his history of later imperial China, but is most clearly presented in his chapters on the politics of the later Ming emperors, pp. 598-685,
 Wang and Dincecco, "Violent Conflict and Political Development Over the Long Run," 350.