The Journey is Half the Sun is an alt earth (or possibly post-interstellar collapse... it's a little hard to tell) story that involves a culture that's something of an inca/maya/aztec/olmec/etc pastiche with slightly different names. The main characters are set on a journey to the furthest reaches of the continent for some Dreadfully Important Reason (politics or flight, or merchanting or something) and travelling by land takes half of a year - literally (as far as they're concerned) half the life of the sun. The journey is made, from time to time, by the brave or the foolhardy, and it is known that it is possible, but it is by no means trivial. The story focuses on the various trials and tribulations that the group must survive to get where they're going.
and for mine: The Furry Rock of Tennesee, and Other Stories
and for mine: The Furry Rock of Tennesee, and Other Stories