15 not including the revenues from merchants and traders and from all the Arabian kings and the governors of the territories.

Read 1 Kings 10:15 Using Other Translations

Beside that he had of the merchantmen, and of the traffick of the spice merchants, and of all the kings of Arabia, and of the governors of the country.
besides that which came from the explorers and from the business of the merchants, and from all the kings of the west and from the governors of the land.
This did not include the additional revenue he received from merchants and traders, all the kings of Arabia, and the governors of the land.