If King David had 8 wives and his son Solomon had 700 then how many people in Israel didn't come from the ...?

It goes beyond that. Most of the Jews in Ethiopia claim direct descendency thru the Queen of Sheba as one of Solomon's honies. By genetic tests, they have ascertained that there are 16 million people who can trace their ancestry back to Genghis Khan, and he only lived 800 years ago. Solomon has to have that topped.