The population of High Tang(around 750 CE) has been the subject of much debate similar to the population of late Ming. Yet unlike those of late Ming, the Tang was a much earlier dynasty and hence estimation tends to vary for the Tang more than any other dynasty.

According to traditional census, during the 14th year of Tien Bao, the household number was 8,914,709 and the population was 52,919,309, often known as the height of Tang. Yet from various historical records, we know that this number was far from the actual size of High Tang's population.
In fact, the Tang population census was largely unreliable since the inception of the dynasty.

One of the major reason was the problem of migrants. This issue started during Gao Zong's period and became especially serious by Wu Ze Tian's time. Two decrees made during the Kai Yuan era tried to deal with the problem. The first one's exact date is unknown, but it was written by Xuan Zong and mentioned the following:

"Since we have been in a state of peace, people jave become very indolent and dishonest. The laws of the state have sometimes become slack and frauds among the peasants have indeed multiplied. Now, wherever the calendar extends, the lands of our subjects and vassals have no beyond. Yet though the population has grown, the tax revenues show no increase. Men all heedlessly leave their native places and band together to wander in idelness. Sometimes poewrful men provide refuge...The running away frows year by year and the corruption spreads day by day. The prefecture and country officials do not show mercy and the districts and neighbourhoods suffer the harm....In every prefecture the men who have run away to escape military service shall be permitted to give themselves up within 100 days of the day on wich this decreearrives, and in accordance with the regulations shall everywhere be enrolled by households."

From this decree we know that a large portion of the population hid themselves to avoid taxation.

This problem was not solved, and was again addressed in the Jiu Tang Shu, biography of Yang yan: "户部徒以空文总其故书，盖得非当时之实“ It mentioned that the board of registration used empty census and their figures doesn't reflect the actual truth of the time.


A much more thorough estimation was done by Du You in his Tong Dian. According to Tong Dian, Shi Huo: "国家贞观中有户三百万，至天宝末百三十余年，再如隋氏之数。盛唐之盛，迈于西汉，约计天下编户合逾元始之间 比量汉时，实合有加数，约计天下户少犹可有千三四百万矣“
Du You estimated that the actual population of High Tang should be greater than the popultion during the height of Han, with 13 million-14 million households, compared to 8,914,709 on the census. In another word, he speculates that the census was underestimating the population by at least 50 percent. Du You worked in the board of registration for a long time and unerstood its deficiencies. By using his estimate, we can roughly conclude that the population of High Tang was around 80 million.

Furthermore, much of the Tang was ran by Jimifuzhou, and included many ethnic minority which did not enter the registration.

I think it would be nice to just have the estimates for world population at this time, so we get that nice feeling of "whoah Tang is so strong"

Here is a series of such estimates. The world population for the Sui/Tang is a little over 200 millions. This would put China at about 1/3 of the world population (and brw makes the 120 estimation very unlikely...)

http://www.census.gov/ipc/www/worldhis.html

During high Tang in the mid 8th century, the world population is probably around 240 million. What bothers me about some of these estimation is that some estimate the world population in 1 A.D. to be as high as 300 million, yet estimate the world population in 700A.D. to be only 210 million. I suspect the involvement of Eurocentricity of such estimations. For one the population of the most part of the world in 700A.D. grew. The only part where the population declined is Europe. India, Middle East, East Asia, Central and upper Asia, Southeast Asia and even the Americas all have population growth by millions. China's population is at least equal to that of 1 a.d. There is noway the world population could have decreased by 90 million if only Europe declined in populaition, for Europe never even have 90 million in its history up till 3 hundred years ago.

I suppose it depends on what you call Europe... Apart from the mediterranean countries, Europe was probably not much populated in the 1st century AD, and I doubt that its changes before the 8th century had a significant effect on world population.

However, in the first century AD, North Africa and the Near East did have a large population, which went down afterwards. This and the fall of Rome might explain part of the decrease.

A look at the references they give would probably shed some light on the hypotheses the authors used. Anyway, all of this looks pretty much modern and scholarly to me, not much room for bias (eurocentric or otherwise) there...

Francois

Actually even if everyone in the Roman empire dies, it still doesn't explain the decrease since the whole Roman empire even according to the most upper-estimation of modern historians is only around 65-70 million. A 90 million drop is hardly likely. Considering all other parts of the world increased in population. And we have little reason to suppose that northern Africa decreased in population drastically since its Europe that suffered invasion the most.

Can you go into further depth with this? If 15 mou of land is required per mouth, then 120*15=/=1.6 million.

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120 million x 15 mou of land is 1.8 billion mou of land required, not 1.6 million.

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Actually, the problem is probably the figures you give for arable surfaces (650 000 and 1 400 000 mu)... I believe they are wrong by a factor 1000

if you need between 5 and 15 mu to feed one person, then 650 000 mu would feed between 43 000 and 130 000 persons, whereas 1400000 mu would feed between 93 000 and 280 000...

I assume here that mou means mu, ie a surface which corresponds to 1/15 of an hectare, which seems likely from your figure of the 15 mu of dry land per head (1 ha per head in modern terms). I believe this is a little high (an average 6 person household, would need 6 ha just to feed itself, and much more if they used farmhand, this seems a bit too much...), but the order of magnitude is clearly right. So, either you forgot three zeroes at the end of the figures for arable land, or you are confusing two units (the mu, and another mou, which I don't know about, and would represent something like 1000 mu...)

Just for the sake of comparison, nowadays, the province of Zhejiang has over 24 million mu of farmland (including about 20 million mu of paddy)

Francois

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I have updated this topic and edited the original post.

The actual population of the Tang dynasty was underestimated by most sources.