Well, someone's obviously a fan of The Lord of the Rings...
That crossed my mind too, but then I remembered that real world mythology is replete with individual trees having or representing some greater cosmic significance, even if it's only metaphorical. Yggdrasil and the biblical tree of knowledge leap to mind. As does
Jedi Master Ood Bnar.
When was this supposed to have taken place? Is this a reference to old-canon or new-canon? In the old canon the Sith never actually ruled the entire galaxy despite what ROTS says.
Whatever the EU did or did not say is rendered moot since the movies have always trumped everything else, and in RotS, Palpatine was very explicit on the matter.
That aside, I think it's mentioned in the 'Tarkin' novel as well as 'Aftermath'. There's also some oblique references and intimations here and there if one pays attention. The "Old Republic" is mentioned more than once in the prequel-era, meaning that there was an earlier incarnation that fell at some point. Also the idea that there's an ancient Sith shrine on Coruscant indicated that they once had a presence there. Those are just off the top of my head.
If we really want to split hairs though, it seems that nobody has ever truly ruled *the whole galaxy* as there's always patches of unexplored regions, backwaters, fringe empires, independent or neutral systems that neither the Republic nor the Empire really bothered with much. The Hutts for one always seemed to remain mostly a power unto themselves even under the Empire.
I would think the Lothal temple use to be some sort of training desination for younglings or padawans. Or a place of the trials. Perhaps on older version of the Gathering the Jedi did on Illum to get crystals for their lightsabers. Considering that it took two to open the temple, and Ezra got his crystal there.
It's certainly possible. I just wonder at why it would be hidden by design. The temples on Coruscant, Iilum, Vrogas Vas and Devaron all seem to be more or less out in the open, so the Jedi are hardly shy about these things.
I'm not saying that an extended period when the Jedi existed in hiding is the *only* possible explanation, but I think it's an interesting one. It ties in with the notion that the Sith once ruled the galaxy and adds a new dimension to the purpose behind Order 66. Suppose Palpatine came up with the specifically because the last time the Sith took over, the Jedi were able to go to ground en mass and were able to eventually overthrow the Sith rule.
Jedi having to live and train in hiding brings up images of religious pogroms as well as shades of the early 'Starkiller' drafts of Star Wars, with the "Jedi-Bendu" exiled and hunted by the "Knights of Sith". A part of me likes the notion that a version of those events still took place in continuity, only in the very distant past.
