All of the surviving poetry of the Tang Dynasty can be fit into four volumes. All of the surviving poetry of the Song Dynasty can be into 12 volumes. The Ming dynasty would fill hundreds but we do not know for sure because it has never been attempted. The Ming, far more than its predecessors, was a full flourishing of Chinese civilization. The population exploded, wealth poured in from the entirety of the known world, and a truly substantial middle class patronized the arts and letters like no culture anywhere before it. And it was the most prolific period for poetry yet seen. Courtiers, Emperors, and Merchants all wrote poetry.
Yet Ming poetry is rarely collected because today it is rarely read. Among readers Chinese and foreign, the consensus is that the Ming produced very little of lasting note. A few names are known from these centuries, but generally they are ranked below even more minor Tang poets. The Ming produced more poetry and more poets than ever before, but produced far less of quality.
Naively, great art is produced by great artists, and great artists occur somewhat randomly distributed across the world population. Access to education and writing are of course necessary, and very little poetry comes out of societies where aristocrats scorn the arts and the peasants do not have the time or resources to practices them. These are dark ages, and hopefully are a phenomenon strictly of the past. But artistic activity alone is not sufficient to produce good art. History is full of ages where the practice and study of poetry was highly esteemed and much poetry was written, but that nevertheless failed to produce worthwhile good poetry. These are Poetic Dark Ages. Poetic dark ages include, among others, Ming and Qing China, Safavid and Qajar Iran, the early modern Arab world, Muromachi Japan, several spans of Indian history, late Mediterranean antiquity, Eastern Roman Greek, and centuries of each of the various European languages. And the inhabitants of a poetic dark age, the many poets and critics making work of little significance, almost never know that they are in one.
The existence of poetic dark ages stands as strong and disturbing evidence against some common beliefs about artistic production. More unique individual people making art is not a ready solution for producing good art, natural geniuses are not always able to transcend the conditions and standards of their time, and cultural malaise cannot necessarily be diagnosed until after the fact. Art left to itself can be the Avant-garde of a society, but it can just as well chase certain dead ends for centuries at a time.
A potential objection to this phenomenon would be that these dark ages did not actually produce worse poetry, it is simply that the standards of our time have overlooked the hidden gems. Artistic standards change over time and certain works of the global literary canon are there for non-aesthetic reasons, and non-aesthetic reasons have barred certain others that deserve to be there. It’s likely that at least one of the ages I mentioned will be reevaluated within the next century, and while they may not be declared a retrospective golden age, a bronze or silver is quite possible.
But all of them I doubt. These poets have been studied, read and reread over many centuries, been discussed and evaluated by scholars of many traditions, and have never risen to fame beyond their immediate generation. More concretely, it is hard to read the works of late Imperial China or late Imperial Iran and not be disappointed by the fact that any inspired imagery or moving passages can be found better realized by their predecessors. Du Fu and have Hafez have many imitators, but none of their imitators were truly competitive with them. There is incredibly interesting and complex medieval European poetry and it is worthy of preservation, but even the best lacks the power of their ancient predecessors or vernacular followers. Some perfectly competent poetry is just not very good.
It is hard to diagnose a single cause for these events broad and scattered as they are, but certain common factors are worth dwelling on. The civilizations that produced poetic dark ages had a set of cultural standards and expectations around poetry. Part of the reason that later Chinese poetry never equaled Du Fu or Li Bai may have been that they all knew Du Fu and Li Bai as the models they were trying to imitate. Even as the Ming expanded access to poetry, the forms themselves never changed. Thus an upper middle class woman writing poetry about her own life, something that would have been unthinkable to the narrow group of educated male courtiers in the Tang, was not able to rival her famous predecessor because she was restricted to the same rules, the same expressions, and the same emotions. Poetry was an august ancient art, and to break the rules would be to do something other than writing poetry: too much respect for the past hindered the present.
This is why certain shifts in poetic practice have led to extremely productive ages of poetry. The shift to the vernacular language all around the world has produced incredible, and the further shifts brought about global modernity (colloquial language over formal, topics previously banned, etc). Novelty often gets mistaken for genius, but the two usually coincide. The Ming and Qing are considered dead ends for poetry, but are now revered as the defining age of Chinese prose thanks to the great novels written in the vernacular by semi-anonymous obscure scholars. The were fundamentally embarrassed to write such vulgar works in contrast to the elegance of the ancient practice of poetry, but it is these works that have stood the test of time. Haiku, now considered to represent the ethereal essence of the Orient, was originally a vulgar middle-class form of poetry rebelling against the more refined Waka tradition.
It is not always the case though that the new is enough. Petrarch, the original theorizer of Dark Ages, thought that he was commencing a new chapter in Italian poetry after the great achievements of Dante and himself in the vernacular. Yet the time after Petrarch is sometimes called the century without poetry. Dante himself was highly inspired by the court poets of Frederick II who wrote in the Sicilian vernacular a generation before but are now largely forgotten. Dante and Petrarch are enough by themselves for a golden age, but the maturity of Italian vernacular poetry took centuries and did not produce the permanent flourishing Petrarch had hoped for.
Poetic Dark Ages have been undiscussed and unnoticed largely because of the strange situation European languages, especially English, have found themselves in over the last 4 centuries. The prosperity to write poetry has consistently been followed by further growth in education, access, and in new styles and subject-matter. The first vernacular poets were followed by the poets of the Enlightenment, the Romantics, and straight into modernity, each generation discovering new forms based on new conditions in the wider world. Premodern English poetry was never mature enough to have strict rules and constant societal change prevented any settling. Books printed in other lands provided stimulus whenever a tradition risked becoming stale.
Now we have more people writing poetry than ever before, writing in more styles than ever before, writing and translating in more languages than ever before. It would seem that we live in an age of permanent innovation, and permanent flourishing. But poets who live in dark ages never recognize them.
"In contrast with the rich poetic world of Tang and Song, the Ming is characterized by epic works such as Water Margin, Journey to the West, and The Plum in the Golden Vase. In contrast with the naive sculptural arts of Tang and Song, the Ming, especially in the period 1426 to 1620, is characterized by elaborate taoci ceramics and the red tihong and polychrome tianqi lacquer ware. And from the standpoint of scholarship, in contrast with the Buddhist philosophy and Confucian prosperity of Tang and Song, the Ming might be characterized by a vacuity of creative power."
Watsuji Tetsurō. "Who Was Confucius?"