One of the most famous and useful "travel foods" was pemmican, used by the Aboriginal people of the North American plains and later by Metis as well as the voyageurs who came into contact with them.

It was essentially lean dried meat pounded into a kind of powder, then mixed with fat and sometimes berries or choke cherries etc. It is extremely high in protein and lasts for a very long time. It was also adopted by Arctic and Antarctic explorers because it was high in nutrients while being portable and long-lasting.

It has a parallel in Russian Tolkusha which is the same concept but fish meat instead of the more common buffalo used in pemmican.

I've tried it, it is quite unpleasant.