The Inca road network

The Qhapaq Ñan ran some 40,000 kilometres from present-day Colombia to Chile. Chaski runners worked in relay between stations a few kilometres apart. What they carried was largely khipu — knotted cords, a system we still cannot fully read, but which certainly encoded numbers and probably more. The bridges of braided ichu grass were re-roped every year as a communal obligation; the last of them, Q'eswachaka, is still renewed each June. The absence of the wheel is not a deficiency: in that terrain, llama trains and staircases are simply better.