The Song state established a Maritime Trade Office (shibosi) in Quanzhou to manage overseas commerce, taxes, and shipping-related administration. Concentrating trade through regulated ports increased traffic, information flow, and demand for dependable sailing knowledge. Over time, these conditions encouraged better route knowledge and mapmaking tied to real shipping practices.
In the Dream Pool Essays, scientist Shen Kuo explained how a needle could be magnetized and noted that it would not always point exactly due south. This kind of practical discussion helped turn magnetism into a tool for measurement rather than a curiosity. It set the stage for later, more explicit descriptions of compass use in seafaring.
Writer Zhu Yu described how ship pilots navigated using stars and the sun, but relied on a “south-pointing needle” (magnetic compass) in dark weather. He also noted practices like sounding the seabed to identify location by the mud’s look and smell. Together, these details show that Song-era navigation combined instruments, environmental observation, and experience—conditions that supported the making and use of practical sea-route charts.
In the Mediterranean world, “portolan charts” became known for dense coastal detail and networks of directional lines based on compass bearings. These charts were designed to support practical sailing from port to port, especially along coasts. This matters for Chinese nautical cartography because historians often compare Chinese route charts and bearing-based sailing directions to the portolan tradition when discussing shared navigational problems and different mapping solutions.
Between 1405 and 1433, Ming-sponsored expeditions led by Zheng He sailed through Southeast Asia and across the Indian Ocean. Even though the surviving maps are later copies, the voyages helped standardize knowledge about ports, sailing legs, and bearings over huge distances. That accumulated route knowledge later shaped Chinese navigation materials compiled in the Ming period.
By the late Ming, navigators and merchants used written sailing instructions (often called “pilot books”) that paired compass bearings with distances and sequence-of-ports knowledge. These texts supported repeatable routes even when coastlines were hard to see or when sailing at night. Such pilot-book practices are closely linked to the development of route-based nautical cartography, where the route itself—not a scaled coastline—can be the main organizing feature.
The Selden Map is an early 17th-century Chinese map centered on the South China Sea and marked with maritime routes and compass bearings radiating from the Fujian coast. Unlike many traditional maps that emphasize an administrative view of territory, it highlights commercial sea connections among ports in East and Southeast Asia. It is widely treated as the earliest surviving example of Chinese merchant cartography that explicitly maps shipping routes.
Mao Yuanyi compiled the military encyclopedia Wubei Zhi in 1621 (later published in the 1620s), including a long strip-style navigation map now called the Mao Kun map. The charts are organized as sequential sailing legs with bearings and coastal waypoints, matching the needs of navigation more than the needs of land administration. As a surviving compilation, it became a major reference for how Ming-era Chinese route mapping could function in practice.
The Wubei Zhi was published in the 1620s, circulating the Mao Kun navigation charts in printed form. Print publication mattered because it stabilized a version of route knowledge that might otherwise remain private or oral among pilots. This helped later historians identify a concrete artifact of Chinese nautical cartography that can be compared—carefully—to other navigation-chart traditions such as portolans.
John Selden described the map (and an accompanying compass) in a 1653 codicil to his will, showing it was in his possession by that date. This is a key reference point for establishing the map’s existence and early history, even though scholars still debate exactly when and where it was drawn. The documentation also hints that navigation tools and charts could travel through complex networks of merchants, sailors, and conflict at sea.
In 1659, the Selden Map became part of the Bodleian Library’s holdings through Selden’s bequest. Its preservation in a major library helped it survive when many working charts and route guides were lost through wear, secrecy, or political change. This transfer also marks a shift: an Asian navigation document began to be curated within a European scholarly institution.
In 2008, historian Robert Batchelor’s examination of the Selden Map drew attention to its plotted shipping routes and its value for understanding early modern East Asian maritime trade. This rediscovery shifted the map from being treated mainly as a curiosity to being studied as evidence of commercial navigation and chart-making. The new attention also led directly to major conservation work, supporting a clearer long-term legacy for Chinese nautical cartography research.
Chinese nautical cartography and portolan charts (Song–Ming, 10th–17th centuries)