Conversation so far:
Did the group Van der Graaf Generator influence many people?
Van der Graaf Generator have inspired several notable musicians, including Rush, John Lydon, Marc Almond, Graham Coxon, Luca Prodan, Mark E. Smith, John Frusciante, Bruce Dickinson and Julian Cope.

Question: When was the group popular?
Self-contained rewrite: When was the group Van der Graaf Generator popular?