Why is it called the Silk Road when nobody at the time called it that?

The name is much younger than the roads. "Silk Road" comes from the German word Seidenstraße, which Ferdinand von Richthofen, a German traveller, geographer and scientist, is noted for coining in 1877. The trade routes themselves were active from the second century BCE until the mid-15th century, so the people who used them never called them by that name. The English version took off later: the term did not gain widespread acceptance in academia or popularity among the public until the 20th century, and the first book called The Silk Road came out in 1938.

Richthofen was not a historian of trade. Between 1862 and 1868 he worked as a geologist in the United States, where he discovered goldfields in California. Then he turned to China, making seven expeditions between 1868 and 1872. His big report on his travels appeared in Berlin from 1877 to 1885, and he paid close attention to the economic resources of the country he crossed.

Richthofen himself coined the plural too, Seidenstraßen, and today some historians prefer "Silk Routes", because the old picture of one road is wrong. It was never a single route from China to the Mediterranean. It was a network of routes, an intricate web of land and sea connections across a huge part of the world. Even Marco Polo, who is often linked to it, never used the term.

So the name is a useful label with a catch: it is a 19th-century shorthand, and the real story is bigger, messier and older than the single line it suggests.