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And the people referenced here do mean "early modern," that is, the Qing from around 1644 to 1800. So I doubt that mentioning the total collapse of China in the mid-19th century would be too relevant here.

The quote is from Victor Lieberman's Strange Parallels, a monumental piece of comparative world history that looks at Eurasian history from 1000 to 1800:
In terms of territorial conquest, internal stability, cultural circulation, and economic output, the Qing may have been the world's most successful early modern dynasty. The Manchus' tiny numbers and fear of being overwhelmed seem to have bred an unusual esprit de corps, an acute sensitivity to disorder, and a compensatory determination to demonstrate their Confucian bona fides. Perhaps because they adhered not to Chinese primogeniturial succession, but to the Altaic system of "tanistry," which allowed them to choose the most capable heir, the Manchus also enjoyed a greater share of effective monarchs than the Ming. What is more, to follow Sugiyama Kiyohiko, within the administrative system inherited from the Ming, the early Qing inserted a network of personalized loyalties that derived from their specifically Inner Asian background. In combination, these features let the Qing revitalize a system that had shown serious signs of exhaustion.​

While Lieberman is primarily a historian of Southeast Asia, William T. Rowe, who wrote a substantial portion of the Cambridge History of China's volume on the Qing, concurs:
[18th-century Qing China] was a time of relative peace and prosperity but also of vigorous growth and change. Domestic unrest was largely absent. The population grew dramatically, due in large part to a declining mortality rate, as disease and malnutrition were better controlled than in the past. The geographical scale of empire grew enormously as borderlands on all sides were effectively incorporated. Internal expansion was also impressive, with China's traditional lowland civilization moving uphill--clearing and settling highlands--and with the reclamation of massive stretches of seacoast, lakeshore, and riverbank. Agricultural output expanded greatly in aggregate, and productivity intensified, certainly per unit of land and possibly per capita as well. Commerce and industry likewise intensified, and regional patterns of exchange began to coalesce into a vast national market. Overseas trade with both Southeast Asia and the West recovered from its seventeenth-century depression and underwent a steady growth unaccompanied by serious diplomatic tensions. The mid-eighteenth century also saw a continuing rise in literacy and popular education, a further expansion of publishing and the print culture, and a flourishing of the arts, perhaps most notably in the theater and the novel.

There were many causes for all of this, but political factors certainly played a part. The era saw a remarkably high level of bureaucratic discipline and morale, spawned in good measure by unusually capable and energetic occupants of the throne itself. Potentially devastating ethnic tensions within both the ruling elite and the overall society were kept in check. A complex currency system was managed with great success. Fiscal stability was brilliantly achieved, with the burgeoning economy tapped to provide a comfortable level of government finance without increasing, and probably even reducing, the popular tax burden. The empire's hydraulic infrastructure, all-important for purposes of flood control, irrigation, and (increasingly) commercial transport, was effectively maintained, indeed greatly expanded, despite population growth. The bureaucracy of "high Qing" enjoyed nearly unprecedented success in managing the massive problems of food supply and food prices and in controlling instances of local or regionalized dearth. Not least, it demonstrated satisfactory responsiveness to the accelerating rate of civil litigation and provided facilities for popular conflict resolution.
So were the Qing indeed the most successful dynasty to exist between c. 1500 and c. 1800?
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