Du You (Chinese: 杜佑; pinyin: Dù Yòu; Wade-Giles: Tu Yu, 735–812), courtesy name Junqing (君卿), was a Chinese scholar, historian and prime minister of the Tang Dynasty, who devoted thirty-six years to the compilation of the Tongdian, a historical encyclopedia with 200 sections (volumes), a collection of laws, regulations, and general events from ancient times to his own. He was born to an official family in what is now Xi'an, Shaanxi, almost eighteen years before the abrupt rebellion of An Lushan.

He was a client of Wei Yuanfu (韦元甫), and "a political thinker on a grand scale"; comparable to Ibn Khaldun. While working in Wei's staff for the military government of Huainan, in 766 he began the Tongdian.

Exemplary translation:

from Food and Money: Regulations concerning land property, Translated by Ulrich Theobald.

Grain is the arbiter of human destiny; earth is the breeder of grain; man is governed by his lord. If there is grain enough, a country is well equipped; if the (possession of) soil is rectified, people have enough to eat; if the inhabitants are examined well, labour services are equally distributed. A ruler who is aware of these three crucial points, has a well governed country [...]

In the 25th year of the era Kaiyuan "Opening the Origin" (738) of the Great Tang dynasty, an edict said: A field of the seize of one mu shall be one pace broad and 240 paces long; one hundred mu are one qing. A male adult is given a field of 20 mu for lifelong cultivation (yongye), and a personal field (koufen) of 80 mu; young men above the age of 18 are also given the same amount like male adults. Old men, seriously ill people and people with incurable diseases are only given 40 mu of personal field; widows, wifes and women are given a personal field of 30 mu. Persons that were first to obtain a lifelong cultivation field, all obtain the full amount of personal field. Babies, children, young an adult men and women as well as old and sick persons, widows, wifes and women that live in the same household, are all given a field of 20 mu for lifelong cultivation, and a personal field of 20 mu seize [...]

As field for lifelong cultivation, the princes as relatives of the emperor obtain one hundred qing, the officials of superior first rank obtain 60 qing, princes in commanderies and their officials of vice first rank obtain 50 qing, the dukes and their officials of superior second rank all obtain 40 qing [...]

In the era Tianbao "Heavenly Treasure" (742-755), all in all field of the amount of 14,303,862 qing and 13 mu were distributed.