The Cabal is 26,000 year old give or take (since the Atlanteans descended into such evil), but yeah, it's still thousands of years old at this point.
And Q has been at this since at least JFK.
I don't know much but here's what I consider to be more or less correct basics.
Tens of thousands of years ago the civilization of Atlantis was very technologically advanced and had spaceships and a big city in the general area of the Bermuda Triangle (their malfunctioning tech is the reason for disappearances of ships and planes to this day). 26,000 years ago the Cabal was formed with the goal of enslaving the entire planet. The major superpowers at that time on the planet were Atlantis and Lemuria, akin to US and Russia today, so the Cabal engineered a war.
Since mis-using advanced tech for wars isn't exactly going to end well, it culminated around 11,500 years ago when the Atlantean fleet glassed the Lemurians (located either at today's Gobi desert or in the Pacific depending on the source; more likely Pacific) and the Lemurians pulled an asteroid from the belt between Mars and Jupiter (ironically also a remnant of past wars) and smashed it into the Atlantic ocean. This is why you have things like Ring of Fire and tectonic plates acting up all the time. This event is described in the Bible as the Great Flood.
The last sane people from these once great nations fled into the Pleiades cluster and the surface Earth humanity was literally blown back to stone age. From then, the rest is more or less known history with various forces acting behind the scenes (Good aliens with a base on Mt. Olympus helping Greeks form a democracy and being worshipped as gods, Cabal orchestrating barbaric wars and invasions, etc etc…).
Yes, the Alliance against the Cabal. Good that you mentioned it. I oversimplify sometimes.