What to expect
A channel cut into rock and a museum inside a stone religious complex offer very different views of history. Use Cajamarca city for Belén and Cumbemayo. It is a manageable introduction without pretending you have seen the entire department.

How it fits into a journey
You can fly from Lima and start in the city. Arrange onward travel to the coast or Amazonas only after checking the actual transport; map proximity is not a connection.