Mencius - Book 5, Part 2, Chapter 2B

'To the Son of Heaven there was allotted a territory of a thousand lî square. A Kung and a Hâu had each a hundred lî square. A Pâi had seventy lî, and a Tsze and a Nan had each fifty lî. The assignments altogether were of four amounts. Where the territory did not amount to fiftylî, the chief could not have access himself to the Son of Heaven. His land was attached to some Hâu-ship, and was called a FÛ-YUNG.

'The Chief ministers of the Son of Heaven received an amount of territory equal to that of a Hâu; a Great officer received as much as a Pâi; and a scholar of the first class as much as a Tsze or a Nan.
~ James Legge translation via nothingistic.org ~

Go here to read the introductory post to this serialized version of the Works of Mencius.