The historical demography of Japan to 1700The second cycle encompassed the prehistoric Yayoi, protohistoric Tomb, and the fully
historical Nara (710–794), Heian, and early part of the medieval period, to about 1300–1500.
Between 900 bce and about 800 ce, Japan’s population grew rapidly to over six million, as new
livelihoods, such as farming, were introduced, and new and better tool technology became
available with the transfer of iron and other metals, all from Korea. Beginning around 800,
Kitō reasoned that Japan’s population had reached the limits of growth possible under the
contemporary agricultural and economic regimes. The causes for this long period of demo-
graphic stasis were left unclear in 1983; in the 2000 work Kitō cited the effects of killer epi-
demics and famines as possible reasons for that downturn. More problematically, Kitō had
drawn his figures for population during the early tenth and late twelfth centuries from land
records, assuming that the land had been measured accurately and that almost all residents of
the archipelago were rice farmers.
The third cycle began between 1300 and 1500 and ended during the 1860s. Once again, new
technologies, better crop yields, and more land under cultivation fed a long growth cycle that
lasted until around 1700. Kitō inferred a mammoth population for Japan in 1700: over 31 million.
Beginning about 1720, Japan’s population once again reached the limits of growth under that
system, as famine, disease, efforts at population control, and other factors held the population
steady at about 30 million or slightly less.
The final cycle coincided with the development of modern Japan. Beginning in 1870, popu-
lation multiplied, held back only by the disaster that was World War II. After 1945, the popu-
lation picked up where it had left off and reached a high of about 123 million in the early 2000s.
Beginning around that time, Japan’s population commenced to shrink, primarily because of low
fertility and the rapid aging of the populace. By 2050 or so, Kitō calculated that Japan’s popula-
tion will have dropped to about 75 million.
Based as it is on the available figures for Japan’s long past, Kitō’s work provided a brilliant
synthesis that was breathtaking in its scope. Even today, it is the starting point for any discussion
of Japan’s demographic history. Scholars have, however, raised some questions about Kitō’s first
two and a half cycles.
First, the figures for the prehistoric Jōmon period were based on the work of archaeologist
Koyama Shūzō during the 1970s.^2 He used contemporary archaeological remains and many have
expressed skepticism about his research methods.^3
Second, Kitō reasoned that the population of eighth- century Japan was around six million,
based on the venerable work of Sawada Goichi during the 1920s.^4 Today, nearly all historians
accept a figure of six million for the eighth century, but apply Sawada’s number to differing
decades and thus view the late 700s as an era of sizable growth or the beginning of stasis.
Third, Kitō’s methodology for deriving population estimates for 900 (about 6.4 million) and
1150 (6.8 million) are open to considerable doubt. Kitō used two records purportedly including
all the rice paddies under cultivation and then divided that total by the amount of land supposedly
necessary to support one person during the 700s. Both Charlotte von Verschuer and I have been
roundly critical of Kitō’s method.^5
Fourth, Kitō left the date for the transition from the end of cycle two to the start of cycle
three unclear at 1300–1500. And fifth, Kitō never explained how the violent and famine- ridden
Warring States’ period could have been a period of rapid growth, to as many as 15 million. Not-
withstanding these considerable doubts, however, Kitō’s theory of the four cycles remains the
most widely accepted interpretation of Japan’s demographic history.