What is Axis Mundi
All of the stars appear to rotate around the celestial poles. The only exception is the North star, currently represented by the star Polaris. We can illustrate this movement with long exposure photography. Knowing this for millennia, the ancients imagined an invisible pole going through the center of the Earth. (hence the pole-star) In other cultures, this “line” represented a spindle, a mountain, or a tree, to name a few.

Druids, and the Christmas tree as the Axis Mundi
Besides the pole, the motif of a tree is still very popular in western culture. We can witness this every Christmas. The evergreen pine tree represents this eternal, world tree. The largest star on its top represents the polar star. The rest of the decorations stand for the other luminous bodies, while the ribbon represents the Milky Way.

Another reason why our ancestors chose the pine tree is that its shape helps us visualize the rotation of the universe. It represents a gigantic cosmic chakra – a whirlpool essential for the very existence of the universe.
Druids and the world tree
Galo-Celtic Druids, just like Slavs, revered the oak tree the most (even though other trees were worshiped as well). But which oak was “the tree of life” is the question. In my opinion, it was the holly tree – an evergreen oak, very similar in shape to the pine tree. The holly tree has always been popular as a Christmas decoration in the west. It was also sacred to Druids.
In Balkans, the “holly tree” is Bozhika or Bozhikovina – a name that comes from the Slavic word for Christmas – Bozhic, meaning that its use for this purpose is very ancient. Unfortunately, for the same reason, this tree is now almost extinct in Balkans. The pine tree replaced it during the Christmas celebrations.
But back to the Druids. According to Wikipedia, a reconstruction of this native Gallo-Celtic word goes as follows:
“The hypothetical proto-Celtic word was *dru-wid-s – “oak-knower”. from the PIE roots *deru- tree and *weid- “to see”. Pliny the Elder supported the meaning “oak-knower” (“oak-seer”)
Whenever an etymology of some ancient word sounds Slavic, it gets the label “Proto-Indo-European”. I really don’t know why is that, but let’s just say that the tree is called “drvo” or “dervo” in all Slavic languages. The same goes for the verb “to see”, “to know”, which has the root “vid” in all Slavic languages.
Moreover, the idea of “knowing the tree’ is at least as ancient as Bhagavat Gita. The Sanskrit root “ved” also means “to know”:
“There is a banyan tree which has its roots upward and its branches down, and the Vedic hymns are its leaves. One who knows this tree is the knower of the Vedas.” (BG 15.1)
Tree-rings as the yearly markers
It takes approximately one year for the tree-ring to form in the cross-section of a tree trunk. It takes the same time for the Earth to orbit around the Sun. Moreover, the shape of a tree’s cross-section matches perfectly the shape of the Earth’s orbit.
However, only in some Slavic languages, we see the parallel “god” – tree-ring, and “godina” – year. This is a very ancient connection, rooted deep in the language. The fact that the tree-rings represent the yearly growth of a tree became popular in Western Europe with Leonardo Da Vinci.

The Whirling Dervishes and the Axis Mundi
Speaking of this topic, we should not forget the Whirling Dervishes. Most of the linguists will not agree that the words “Dervish” and “Druid” are related. Apparently, the word Dervish comes Persian “darvesh, darvish “beggar, poor,” hence “religious mendicant”. Nonetheless, the similarity between these words did not go unnoticed. There are authors (including myself) who believe that the words are in fact related.
I say this because the purpose of the whirling is virtually the same as the symbolics of the Christmas tree and the Axis Mundi:
“The dervishes aim to reach the source of all perfection through abandoning ego or personal desires, by listening to the music, focusing on God, and spinning one’s body in repetitive circles. This is a symbolic imitation of planets in the Solar System orbiting the sun.“
Source: https://en.wikipedia.org/wiki/Sufi_whirling

Final thoughts
Unfortunately, most of the historians are completely clueless about astronomy and see everything related to the Sun. But the rotation around the Axis Mundi was equally important to the ancients. A separate article about the polar star mythology is below.
Secondly, if we accept the fact that the rituals of the Dervishes and Druids could indeed be related, it would be interesting to try to determine when this happened. And the options are many. It could have happened in Turkey, with the Phrygian tribes arriving from Balkans already in the second millennium BC. But since this sort of mythology exists even in Siberia, perhaps it came from the east with the Scythian and Sarmatian tribes. Or it could have been brought much later by the Gauls who founded Galatia in Turkey.
Regardless of the answer, we can see on this example of how archaeo-astronomy can give us a deeper insight into ancient history, there where archaeology is of no use. It is a shame that mainstream history still stays away from these tools.
More on the Polar star myths:
https://templewilderness.files.wordpress.com/2015/12/alchemy-o9a-v31.pdf