I hear people talk about things like "when Libertarianism started", and "Mercantilism ... spanned from the 16th century to the 18th century". If you talk about that, you are being stupid.
Philosophies are ideas. They have no time period; no one invents them. Ideas can have a first believer, but if the idea isn't a history-based religion or something dependent on technological prerequisites, if it's a general philosophy, then almost for certain the first human believer was long before recorded history and there have been thousands in the world at any time since the beginning of recorded history. The first believer of a philosophy is completely irrelevant to any discussion of the philosophy anyway.
It's not necessarily useless to talk about the time period an idea was popular for, but that's not how the Investopedia article presents it. They say it "was a system ..." and that it "spanned from X to Y".