[justsomehnguy]

>> the ancient trade and military route located on the shortest distance (ca. 70 kilometers)

https://en.wikipedia.org/wiki/Don%E2%80%93Volga_portage

[wumpus]

Wow, that was used for a long time. The Greek one was 700 years.

[Kon-Peki]

There is another in North America that was used for thousands of years before the French found it:

https://en.wikipedia.org/wiki/Chicago_Portage