Adam Clarke on 1 Kings 4:34

There came of all people to hear the wisdom of Solomon - We learn from 1 Kings 10, that the queen of Sheba was one of those visitants, and perhaps the most remarkable, as we have the particulars of her visit, but not of the others.

It is astonishing that of a person so renowned for wisdom, so little should be left to prove the truth of a fact of which all the civilized nations of the world have heard, and of which scarcely any man has ever doubted. The people that came from all kings of the earth were probably ambassadors, who came to form and maintain friendship between their sovereigns and the Israelitish king. We cannot understand the place as speaking of people who, either through an idle or laudable curiosity, came to see and converse with Solomon; to give free access to such people would ill comport with the maintenance of his dignity.