Demographic History of China

I have found a German web-site that is a real treasure-trove of historical fact. They have a section about the demographics of Imperial China; unfortunately it only tackles it from the Yuán Dynasty onward.

The site provides information for Imperial China that I have slightly re-adapted (original here):

Estimations for the population figures of Imperial China vary considerably. They are mainly based on censuses in which households were counted (please refer to my previous post about the Door-Tablet 門牌). The geographic area for which population figure estimates apply depends on the historic situation and the fluctuations of the size of the Flowery Empire; the difference in areas for which population figures are given has thus to be taken into account.

1368: End of Yuán Dynasty 元朝; China's population estimated at 60,000,000
1550: China's population estimated at 120,000,000
18th century: Agricultural Revolution in China : triple cropping of rice; introduction of new crops (maize, potato, sweet potato) lay foundation to sustained population growth
1700: China's population estimated at 100,000,000
1750: China's population estimated at 180,000,000
1795: China's population estimated at 300,000,000
1842: End of the First Opium War; Chinese emigration increases
1850-1864: Tàipíng Rebellion; China's population contracts from est. 408,359,000 in 1851 to 369,282,000 in 1864
1860's: The opening of ports to international trade and the attempts by the Zǒnglǐ Yámen 總理衙門 [the Imperial Chinese equivalent of a Ministry for Foreign Affairs] to establish a Chinese industry kickstart a trend toward urbanisation, especially in ports such as Shànghǎi 上海 (Lower Yángzi) and Tiānjīn 天津 (North China)
1861: Inner Manchuria open to immigration of Hàn Chinese
1900: China's population 400,000,000 (based on a census of counted households)
1911: Chinese Revolution; population given at 427,662,000