One might think that Rean has obtained a lot of materials from his blacksmithing gig during his time in the Demon Beast City. However, what he got were all Heaven-level ones. It was simply impossible to use them for those at the Core Formation Realm and below in the Freedom Sect. With that said, they needed lower-level ones.
Fortunately, it wasn't as if Kentucky couldn't identify their locations. It's just that Kentucky never cared about any ore below the Heaven-level. Malo then requested him to at least point the directions where they could find ores so that missions could be given to the sect members. That's how they found most of the low-level materials for Rean to start his teachings.