 Although the opening titles claim the film was based on "the diary  of the monk Gaspar de Carvajal", director Werner Herzog (qv) has  stated that there is no historical basis for the story and that the  monks diary was invented to lend it more credence. However, a diary  of Carvajal does in fact exist, but Carvajal was not part of any  expedition with Aguirre, but rather part of one 20 years earlier to  the interior.