It looks like the first focus groups were during World War II to “examine propaganda” and that the term “focus group”, itself, might not even have been created until the 90’s.
After spending forty-five minutes trying to find an image that was interesting/compelling/educational about focus groups, marketing, or even think-tanks, I gave up. Pictured is a private mountain built on top of a doctor’s penthouse, by said doctor, in Beijing. He transported rocks and other materials via the service elevator for six-years before the city government found out and told him to take it all down and the other residents suddenly became concerned that he compromised the integrity of the building. He’s a doctor, not a civil engineer.