Not to be a MA Historian Elitist
Pankratian as a form of combat existed all the way back in the times of Ancient Greece. This form of combat involved wrestling, striking and submissions. In fact, it was present during the Ancient Olympiad Events.
When the Romans took over Greece and integrated their culture, they took Pankratian practitioners and began tying/lacing covers onto their fists in the forms of cestus. At first they were simple wraps, but the Romans began fashioning the cestus with spikes and blades. This turned Pankratian into a blood sport and continued to evolve into the Gladiatorial events where the fighters began to fight to the death.
Where Lee is truly a revolutionary force in the history of Martial Arts, is that during the height of the MA Renaissance of the 70's Lee was willing to openly denounce the traditional philosophies of the Martial Arts "Masters" that were widely accepted. Where forms, kata and strict adherence to the spiritualistic "zen" approach of Traditional Martial Arts were held as the end-all/be-all law of practitioners world wide, Lee decried it for being ineffective and obsolete. His research and creation of JKD was the embodiment of his efforts.
However, he wasn't the only Martial Artist that thought that way. Other famed practitioners like Mas Oyama and Gene LeBell were also under the same philosophy. It just so happens to be that Lee was the most prominent/famous of them all (having 6 world wide release movies works well that way).
It doesn't matter if you agree or disagree
... As long as I don't bore you and I spark a moment of thought, my goal is achieved
Queng leon queng tigre ecu tacacut, queca pa? - Pampangan Mandarigma Motto