@ hamster bait
Proverbs was written by Solomon & he did have conversations (or more) with the Queen of Sheba. In additon he had many wives that were not worshippers of YHWH. It's possible that he could have received this knowledge form them.
Or, God could have given Solomon wisdom, he shared this wisdom with these foreign women, & they took it back to their kingdoms, and backdated the artifacts. Who would know?