The greatest mystery of Ancient India or rather medieval history perhaps remains the mystery of why India’s greatest cities fell. During the peak of the Gupta Empire and a few centuries afterwards, we find the greatest of urban centers and cities in the World were in India, teeming with universities, gold, trade, and the finest of silks and the greatest of the legal systems in the world at that time. But by the end of seventh century, an urban decline had begun. This period of hyper unexplained urban decline leads way to the invasions of early Muslim kings into Northwestern India. And could potentially show us why Hindu empires and powers were weak in terms of technology and war stratagem.
Also read: Was Buddha really anti-caste?
So much so that Fâ-Hien, the Chinese Buddhist traveller, while describing Central India in A.D. 399 says “The cities and towns of this country are the greatest of all in the Middle Kingdom. The inhabitants are rich and prosperous, and vie with one another in the practice of benevolence and righteousness. Every year on the eighth day of the second month they celebrate a procession of images. They make a four-wheeled car, and on it erect a structure of five storeys by means of bamboos tied together. This is supported by a king-post, with poles and lances slanting from it, and is rather more than twenty cubits high, having the shape of a tope. White and silk-like cloth of hair – is wrapped all round it, which is then painted in various colours. They make figures of devas, with gold, silver, and lapis lazuli grandly blended and having silken streamers and canopies hung out over them.” 
The travel records of Fa-Hien indicate a buzzing urban Indian landscape, as the famed book of R.S. Sharma, Urban Decay In India, too describes. There is no doubt that India had a host of Urban centres highly successful and served even as international trading centres of knowledge and cultural exchange. Even during the Roman Times, Nagarjunakonda (now the modern region of NagarjunaSagar) served as an important centre of trade and international exchange, boasting a Roman amphitheatre built in the days of extensive trading with the Romans. The region of Andhra itself was known to be littered with extensive urban cities and towns trading with the Roman Empire and experiencing immense prosperity. Amita Ray’s famed work, Life and Art of Early Andhradesa, even says, “Andhra profited much by the Indo-Roman trade and gold flowed into the cities of the country. The rich trading community and women of the royal families generously patronised the arts and gave freely for religious causes. The amphitheatre of Nagarjunakonda is a product of this cultured atmosphere.” 
While many mainstream academic historians like R.S. Sharma in his famed work, Urban Decay in India, do agree that India once experienced a boom of urban cities and urban culture. The causes for its rapid and unclear decline is what remains a field of study that is extremely controversial and lacking clarity. While R.S. Sharma suggests that it is because of purely economic causes amongst a host of other complex reasons he suggests. The rebuttal against it too is valid, suggesting that entire urban centres collapsed solely due to gradual but slow drying up of trade is oversimplification of history. 
In fact, another travel record written by another Chinese traveller in the 7th century while talking about the once flourishing centre of Kushinagara describes it as “The capital of this country is in ruins, and its towns. and villages waste and desolate. The brick foundation walls 86 of the old capital are about 10 li in circuit. There are few inhabitants, and the avenues of the town are deserted and waste.” While this work describes the particular Kushinagara in urban decline, there are various other descriptions of cities still engaged in trade and having thriving urban populations. What we can gaze from this fact is that the decline was gradual but still pretty rapid. 
If one were to study K.A. Nilekanta Sastri’s famed work, The Cholas, he too describes the palatial port cities of Tamil Nadu, engaged in international trade, marvellous sea facing bungalows and endless night beach parities where foreigners and locals alike celebrated with trade and free exchange of ideas taking place. While Sastri sites numerous Sangam records to back up his claims his work is often criticised for highlighting the role of Brahminism and Sanskrit in building a thriving economic and social ecosystem for the Ancient and Medieval Indian sub-continent. 
Perhaps the shadow of Marxist history and the obsession to look at history as a mere class struggle, or rather to fit history into the frame of the class struggle thus far has resulted in historians only trying to find purely highlight economic reasons. Of equal fault are Right Wing historians who attach the blame of fall of urban centres in India solely to Muslim invaders. Both history suggests are far from the truth.
What major mainstream historians have ignored are predictions made in the Puranas about the decline of large scale urban centres, historians like Vijay Kumar Thakur, in his article in 1997, highlights that Varahamira in the Brihatsamhita through his astrological predictions along with Puranic records are actually suggesting why urban centres fell through the use of prediction. This is sometimes used extensively in Indian history by scholars, who state that Puranas merely are written after the event is taken place, and Brahmins to add legitimacy to their religious power in claiming that the piece of writing is a prediction and not a description. 
A pretty credible theory indicating ecological and environmental and geographical issues as the cause as pushed by Vijay Kumar Thakur as he presents the predictions by Varahamira is the idea that extreme de-forestation and over cattle grazing lead to damaging of the ecology of the particular region, effecting rain patterns, resulting in shortage of grains for an overflowing population due to over-migration of foreigners and tribals who previously dwelt in rural centres into urban areas caused gradual urban decline according to Thakur.
But there seems to be another important reason. Thakur himself talks about how Varahamira predicts breakdown of caste and varna order, and overall destability of society. But how does the breakdown of varna order effect the economy and social aspects? D.D. Kosambi, the great Marxist historian, emphasises “With virtual monopoly over land and ritual Brahminism could peacefully reduce tribes to castes”
The earliest expansion of urban centres in the Gangetic valley according to Thakur himself, involved largely the peaceful assimilation of otherwise fiercely fighting tribes and even foreign tribes into the peaceful model of Brahminism which peacefully absorbed tribes and turned them into artisan and merchant castes. The importance of ancestral occupational castes in Ancient India’s economic trajectory has been highlighted by modern scholars like Dr.Radhakrishnan Pillai who says development of products through artisan ancestral castes ensured perfection of goods and services over generations.  Similarly K.A. NilekantaSastri highlights the importance trading guilds set up by various mercantile castes that allowed for easier capital exchange for budding merchants, and exemplary trade The similar reason of shared caste ties is said to have increased modern mercantile prosperity according to India’s New Capitalists by Harish Damodran. 
Even going by Thakur’s ecological theory citing the decline of urban centres, overpopulation played a key factor. Brahminism often played a decisive role in keeping the population under check through its Dharmashastras where cohibition was done strictly for limited procreation and restricted to certain years of a marriage. This often largely evident fact is forgotten in Brahminism’s role in limiting population growth for a long time. 
D.D. Kosambi too always stresses the peace and the ripe climate for economic and social growth Brahminism brought about, by mitigating extreme tribal conflict and repetitive tribal violence between forest dwelling groups as documented even in Ancient Tamil Sangam literature. Many theorists in fact also say the decline of Ancient Indian Urban age had much to do with the collapse of civilisations like the Gupta Empire and great powers who held trade together like the Satavahanas. Satavahanas too despite having tribal origins themselves embraced Brahminism and used it for the establishment of a society that can evolve beyond tribal violence. 
A new look through the prism of how helpful Brahminism was for the creation and thriving of urban centres in India and why its decline due to the rise of religious cults and movements of anti Brahmin nature seem to have occurred in a similar timeline to the rapid decline of Urban Centres in Ancient India deserves some research. While our modern biases against Brahminism and the caste system are rigid, only objective outlook toward history can ever aide us in knowing the full truth.
: A record of Buddhistic kingdoms; being an account by the Chinese monk Fâ–HienofhistravelsinIndiaandCeylon,A.D. 399–414,insearchoftheBuddhistbooksofdiscipline. TranslatedandannotatedwithaCoreanrecension of the Chinese text Page 96
: The History of Theatre by ManoharLaxmanVaradpande Page 233
Urban Decay, Ecological Imbalance and the Brhatsamhita by Vijay Kumar Thakur, Social Scientist, Vol.25, No.5/6 (May-Jun, 1997) p. 13-32.
:Si-yu-ki, Buddhist records of the Western world Page 32
: The Cholas by KA NilekantaSastri&. “Preface”. A Concise History of South India by NooburuKarashima
: Urban Decay, Ecological Imbalance and the Brhatsamhita by Vijay Kumar Thakur, Social Scientist, Vol.25, No.5/6 (May-Jun, 1997) p. 13-32.
: D. D. KOSAMBI, DIALECTICAL MATERIALISM AND THE STRUCTURE AND DYNAMICS OF INDIAN SOCIETY BY D. N. DHANAGARE
: https://www.youtube.com/watch?v=xlHoyvyKA1c – Interview of Radhakrishnan Pillai
: India’s New Capitalists by Harish Damodran.
:METHOD OF POPULATION CONTROL IN AYURVEDIC CLASSICS by PV Tewari and C. Chaturvedi
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M. G. S. Narayanan
Proceedings of the Indian History Congress
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Published By: Indian History Congress
B: ADDRESS OF THE SECTIONAL PRESIDENT: RELIGION, POLITICS AND SOCIETY IN EARLY DECCAN
B.S.L. HANUMANTHA RAO
Proceedings of the Indian History Congress
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Published By: Indian History Congress