Luo Guihuan notes that from the Han dynasty onwards, scholars who were sent to southern China as officials or who traveled there for pleasure were deeply impressed by the diversity of the crops there, and in a spirit of disseminating useful information, many of them wrote down everything they saw or heard, and recommended southern China's resources to the people of other regions.
羅桂環指出，漢朝以降，往華南做官或遊歷的學者，深感當地作物種類的繁多，抱著經世濟物的心理，紛紛記下所見所聞，以對其他地方推薦南方資源。