LISP where EID-to-RLOC mappings originate

LISP uses a map-request and map-reply operation that allows the ITR, the MS/MR, and the ETR to exchange EID-to-RLOC information to populate their LISP databases. But where does the mapping information originate from?

Mapping information for LISP is configured in the ETR using the LISP database-mapping command. This command is typically configured on the CPE (which functions as the ETR) at the LISP site. This ETR contains this information from these commands and provides it to the MS/MR whenever a map request is received. That way the MS/MR populates its database, and in turn, the ITR will also populate its database based on the destination information it has requested over time.

https://networklessons.com/cisco/ccnp-encor-350-401/cisco-locator-id-separation-protocol-lisp#Map-Request_and_Map-Reply