What is Mao Kun map?

Mao Kun map, usually referred to in modern Chinese sources as Zheng He's Navigation Map , is a set of navigation charts published in the Ming dynasty military treatise Wubei Zhi. The book was compiled by Mao Yuanyi in 1621 and published in 1628; the name of the map refers to his grandfather Mao Kun from whose library the map is likely to have originated. The map is often regarded as a surviving document from the expeditions of Zheng He in addition to accounts written by Zheng's officers, such as Yingya Shenglan by Ma Huan and Xingcha Shenglan by Fei Xin. It is the earliest known Chinese map to give an adequate representation of Southern Asia, Persia, Arabia and East Africa.