The academic value of Zheng He's Navigation Chart
 
Of the 530-odd place names on "Zheng He's Navigation Chart," over two-fifths are Chinese, and less than three-fifths are foreign. They are the names of mountains, like Shizi (lion) Mountain; seas, like Jiaozhiyang (Cochin sea); harbors, like Sadi Harbor; shipping channels, like Shuangyumen; islands, like Cuilan Island; reefs and sandbanks, like Baijiao (white reefs); capes, like Nanhuizui; countries, like Champa; administrative areas, like Fujian Province;  and military organizations, like Pinghai Garrison Command. In addition, there were names of temples, like Tianfei Palace; bridges, like Tongjiang Bridge; and pagodas, like Wulishe Pagoda.
 
Thanks to the opening of many new sea routes by Zheng He's ships, the chart shows a wider geographical knowledge of East Africa. It has 16 place names of that area, most of which had previously been unknown: Manbasa (Mombasa, in Kenya), Geerdefeng (Cape Guardafui, in northeastern Somalia), Hafuni (Ras Hafun, in Somalia), Xuduoda Island (an island in north-eastern Somalia), Malindi (Malindi, in Kenya), Zhejilahazela (possibly Djogiri, in Somalia), Mugudusu (Mogadishu, in Somalia), Pulawa (Brava, in Somalia), Lasinake (possibly a head-land in Somalia), Moerganbie (Mereeg, in Somalia), Heier (possibly in Somalia), and the unidentified Muluwang, Qidaer, Muerlihabier, Menfeichi and Gedagan.
 
The chart also shows an advance in the science of geography. It divides shorelines into 11 categories: island, isle, sha (hid-den sandbar), qian (sandbar visible at low tide), shitang (coral reef), harbor, hidden reef, strait, rock, entrance and shoal. At the same time, the land features of some areas are indicated. For example, the island of Ceylon is shown to have two mountains facing the sea in the east and the west, and the area from Ras Hafun to Mogadishu is shown to have hilly land extending all way to the coastline, which is flat and straight. Brava is presented as hilly, Mombasa as a highland area, and Malindi as flat. In the section showing the South China Sea, Shitang refers to the Xisha Islands. Wansheng Shitang Yu on the chart should be Wanli (meaning ten thousand li) Shitang Yu and refers to the Nansha Islands. Shixing Shitang is marked with big and small circles, probably indicating hidden sandbars. Shitang means coral reefs, which were surrounded by shallow sandbars, shoals or hidden reefs made of coral.
   
"Zheng He's Navigation Chart," by including compass bearings, landmarks and astronomical data, as well as reefs, shoals, anchorages, depth of water and other points for attention, was of great practical value for mariners for centuries to come. The numerous place names it records are of value for the study of geography and history. The chart provides clues to the study of geographical changes. For instance, the section of the Yangtze River from Nanjing to its mouth shows Mount Jingshan in Zhenjiang located in the river channel, and Chongming Island having three river-mouth sandbanks (Tieling, Hujiao and Qiansha). It also shows that the mouth of the Yangtze at that time was at Nanhuizui. In addition, Hormuz is painted as an island, which it was at that time.