The Han Chancellor and King of Wei Cao Cao (155–220 AD) made the final significant attempt to limit the power of wealthy landowners. Cao Cao established government-managed agricultural colonies for landless commoners; in exchange for land and cheap equipment, the farmers paid a portion of their crop yield. In the 120s BC, Emperor Wu had attempted to establish agricultural colonies in the northwestern frontier of the newly conquered Hexi Corridor (in modern Gansu). 600,000 new settlers farmed on these state lands using seeds, draft animals and equipment loaned by the government. An imperial edict in 85 AD ordered the local governments of commanderies and subordinate kingdoms to resettle landless peasants onto state-owned lands, where they would be paid wages, provided with crop seeds, loaned farming tools and exempted from rent payments for five years and poll taxes for three years. The edict also allowed peasants to return to their native counties at any time. Subsequent governments of the Three Kingdoms established agricultural colonies on these models. Many scholars claim that Han farmers were generally living at subsistence levels, relying primarily on two documents from the "Hanshu" ("Book of Han"). The first is attributed to the Warring States minister Li Kui 李悝 (455-395 BCE); the second is a memorial written by the Han-era official Chao Cuo 晁錯 (200-154 BCE). Both appear in "Hanshu" Chapter 24, the "Treatise on Food and Money" 食貨志. Li Kui and Chao Cuo both emphasize the extreme precariousness of Han agricultural life, a view summed up by Cho-yun Hsu, who writes that Han and pre-Han farmers had only "a relatively small margin left to meet other expenses": "An account of the income and expenditures of a small farm in the pre-Ch’in (Chan-kuo) period cited in the Han-shu gives a deficit of 10 percent of the annual income, presumably in a year of mediocre crops… In the time of [Chao Cuo] the situation remained very much the same." According to Hans Bielenstein, the physical requirements of subsistence in grain can also be calculated from the "Hanshu": "a family consisting of an old woman, a grown man, a grown woman, an older child, and a younger child, annually consumed 127 "hu" of unhusked grain. This comes to about 10.5 "hu" per month."