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.
Origin
The map is thought by sinologist J.J.L. Duyvendak to have been part of the library of Mao Kun, a collector of military and naval material, who might have acquired it while he was the governor of Fujian. The map was included in Wubei Zhi edited by his grandson Mao Yuanyi, and therefore had been referred to in the past as the "Wubei Zhi chart". In order to distinguish it from other maps in Wubei Zhi, the map was named after Mao Kun by Western scholars such as J. V. G. Mills who studied the map, and therefore came to be known as Mao Kun map in Western sources.
The introduction to the map in Wubei Zhi indicates that the geographical and navigational details of the charts are based on works from the expeditions of Zheng He, and that Mao had "inserted them for the information of posterity and as a memento of [Zheng He's] military achievement". The map is therefore generally considered to be based on maps dating to the time of Zheng He's voyages, and accordingly named as Zheng He's Navigation Map in modern Chinese sources.
According to Mills, the map may not have been the work of a single person, rather it was produced in an office with information added and corrected when new information became available after each voyage. He suggested that this map may have been prepared for the 6th expedition in 1421, with some content added during the course of the expedition, and that the map may, therefore, be dated to around 1422. Others proposed a date sometime between 1423 and 1430. It has also been suggested by J.J.L. Duyvendak and Paul Pelliot that the map may have been partly based on Arab nautical charts.
Format and content
The map was originally in the form of a strip map of 20.5 cm by 560 cm that could be rolled up, but was then divided into 40 pages in the book. The map, after Nanjing and the Yangtze River, shows mainly the coastal regions and islands along the sea route, and places are depicted in their approximate positions along the contour of the coast. The coast of the main land mass is shown largely as a continuous irregular line at the top of the map, with deep V-shaped indentations indicating river estuaries. As a result of the nature of the map and its focus on the coastal region, the shape of the Malay Peninsula cannot be distinguished, and India became elongated as its interior is omitted. Pages of the map are arranged from right to left in traditional Chinese book format, starting from Nanjing and finishing in Hormuz. Places in East Africa such as Socotra, Mogadishu and Malindi appear in sequence from left to right on the coast of Africa which is shown as a continuous land mass at the bottom of the sections for India and Sri Lanka.
Also marked on the map as dotted lines are sailing routes, with instructions given along the route markings. The sailing instructions are given in compass points and distances – the compass point uses a 24-point compass system with a Chinese character denoting each point (each point further subdivided into three), and the distance is expressed in Chinese units of time (each unit a 2.4-hour period) that would take account of the local currents and winds. Most of the instructions are only given in one direction, although occasionally both the outbound and homeward voyages may also be given. The instructions are also more detailed for Chinese waters. The latitude is indicated by the height of stellar constellation, a similar system to one used by Arabs. Four stellar diagrams are given at the end with instruction for positioning the ships in relation to the stars and constellations to ensure correct navigation in two passages – between Sumatra and Sri Lanka, and between Hormuz and Calicut.