Hey there Pakeha,
Always glad to be of help.
Alright, so you dig into really good queries, as usual!
So let's just dive in.
When can we actually date Mediterranean mono-theistic movements?
As was humorously outlined earlier, the evident "first" goes to Egypt around the 1400-1300 BCE range with
Amenhotep IV Akhenaten.
Some consider Marduk of Babylon to be the "first", but I would hazard this assignment as it does not appear that any direct and overt interest was made to remove other deities from worship, or any lowering of tolerance, but instead an escalating of Marduk's position in the pantheon ranks ending in Marduk taking the leading role by around 1500-1300 BCE ranges; though possibly somewhat earlier around 1700 BCE ranges - it's a bit difficult to discern.
However, Marduk's relation is more akin to El's relation to the Canaanite pantheon, or Zeus's relation to the Greek pantheon for folks not familiar with the Canaanite pantheon.
Aten's position, under Akhenaten, is like El or Zeus, but then he takes it a step further and removes monetary funding and official support from the other deity priesthoods.
Once again, we find that the "break" from polytheism isn't uniform and indeed we still find plenty of lesser artifacts from this time period in Egypt which indicate that a continued worshiping of other deities persisted, but at a greatly reduced grandeur.
The most notable shift, then, was in the political theater and not exactly in the common populace; for in the political theater Akhenaten had funneled the power of the divine effectively unto himself and not to a range of varying priesthoods allied to given deities of varying values and psychological dispositions.
Once again, we find the event of stress plays a role here.
It is often easy to miss when looking at Egypt as our common perception of Egypt is that it was so big and mighty that it ran as the default super power in its region until the Romans came along.
This, however, is an idea left to us from the explorations of the 19th c CE before we uncovered and learned much more about the dynamic politics of the non-Greek and non-Roman regions of the Mediterranean region.
Prior to Akhenaten the battles with the Hittite empire were not going very well and the contests over the Levant region had stalled out quite a bit.
It should be pointed out that Egypt was under such stress from in-fighting and external impotence (meaning: their ability to push military might outside of Egypt) that not long after Akhenaten's reign was finished Egypt was shocking the Hittite empire with a request for a treaty by marriage (more on this later below).
Two reigns of destabilization had gone by prior to Akhenaten (this is during 1500 to 1400 range periods).
It should be noted that the Hittite empire was equally having struggles around the relatively same time period, but on a different front with the Kaskians.
Both Empires, while still skirmishing with each other in the Levant, separately were having issues.
The Hittite empire's solution under stress appears to be to invent, by consequence, what we understand today as global politics - they begin to escalate the method of obtaining treaties to subdue or pacify the amount of attacks against them.
Egypt, however, seems to have gone about solutions differently following this and Akhenaten appears determined to unify the momentum of the land.
It does not appear that his endeavor worked very well, however, as it was not long after his death that the original pantheon paradigm is restored and supplies us with the only instance of a monotheistic styling returning to polytheistic styling following the original attempt or movement to conversion.
Now, this could be because Akhenaten never got as far as the Hebrew political push toward an exclusive monotheistic fashion.
The Hebrew peoples could be said to have had an easier time than Akhenaten in this regard due to a complete loss of their land and cultural control following a division of their peoples and would thereafter follow a revolt to re-unify the people into a sovereign nation again.
These kinds of events which aid to act as a natural erasing were not available to Akhenaten, nor to the rise of the Marduk faction in Babylon.
In both of these cases, the pushed for deity was still in the midst a somewhat still thriving civilization - under stress, yes, but still very much alive and with good memory and record of itself.
In this manner, we can understand Akhenaten's "failure" as no real success was accomplished by the unification he outlined and conducted theocratically so following his reign, everyone returned to the original theocratic paradigm (more or less) and returned to political in-fighting that continued to suffocate the nation's strength - to the point Ankhesenamun, Tutankhamun's widow, requests the marriage to the Hittite for treaty in fear - marked fear is pronounced in the letters over rival political factions. She was so afraid that she claims to the Hittites that she fears trusting marriage to her own political family choices.
The Hittite son, Zannanza, was sent and is in fact murdered along the way by a rival political faction (we can only make vague guesses) not wishing to see success - this is how bad things had become in Egypt.
Ankhesenamun gives into Ay, the adviser who wished to marry her and become Pharaoh, and he is a failure at defeating the Hittites and his reign lasts only 4 years.
So, this is the just before and just after section of Akhenaten to give some context to the seemingly odd act of attempting to funnel everything into one deity and one line of power.
It was, again, a perceived solution to the destabilization that was taking place.
However, it did not pay off and the entire pantheon never was truly wiped out successfully so the system not only returned the political divisions (as usually happens), but also returned the religious diversity (as usually does not happen).
So that is a long way of answering the "when" - we can say somewhere abouts 1400-1300 BCE ranges, with a more narrow range of the latter portion of the 1300's.
Perhaps Akhenaten got his idea from looking at the Marduk party success in Babylon; we don't know for sure, so that is pure speculation, but the information of such events could easily have been available should Akhenaten so desire to examine governing solutions.
Can the monotheistic movements be considered independently of their interaction with the Hellenistic world?
Absolutely; we just did.
OK, now; more to the point, can
pure monotheism (as the later Judaism would be understood) be considered independent of their interaction with the Hellenistic world?
No, but yes.
"Yes" in that it COULD have been any culture, but "No" because it wasn't any culture - it was the Hellenistic culture.
That said, I would say that you can't actually understand the Judaic monotheism that came about without first understanding the Hittites, Egyptians, Babylonians, Canaanites as well as the Hellenistic culture.
All of these cultures fed into the Hebrew culture, regardless of Orthodox or Conservative traditions today.
Most of Leviticus' laws are found in the Hittite legal documents, for instance.
The Canaanite pantheon's god of god's is El.
Their language is derived from Phoenician.
They had extensive stay and interaction with Babylon (clearly).
And Alexander did a fantastic job of absolutely dominating the Northern Levant region for a bit and endeavored heavily to "Hellenize" the holy texts and culture as much as he could achieve.
These are just glancing mentions of relations, but the trails go rather deep between these cultures.
More specifically, I think the question could be re-framed as "In what way did the Hellenistic culture influence the Monotheistic movement to occur in the Hebrew culture?" Noting that when we say "Hebrew culture" in this, we are at once accounting for Samaria as well as Judah and Israel.
We start with the Kingdoms of Israel, Judah and Samaria following the effective collapse of the Canaanite "empire" (I would almost rather call this a "league", however, than "empire") following the Sea Peoples desolation of the Levant region low lands.
Israel and Judah had differing ideas of religion, as did Samaria.
These groups could have one day evolved into three diverse versions of Judaism had they all survived, but that didn't happen.
Effectively, Samaria was the only one left after a very short time.
Eventually Judah is permitted its identity again thanks to Achaemenid rule being a bit nicer than the Babylonian rule.
So one variation was by default erased right out; the religious variation of the Kingdom of Israel (keeping in mind that this Kingdom had its own temple system separate from Judah, as did Samaria).
Then comes along Alexander and this is where the Hellenistic infusion begins.
Now, as you can see in
this image, the results of this endeavor upon the North was rather extreme as Hellenistic temples now dotted the landscape alongside synagogues.
The amount of such infusion is more pronounced North of Samaria (as Samaria divided Judah and what would be Galilee and was the Kingdom of Israel before).
Now, eventually a portion of old-time conservative idealists really longed for the land of 400 years ago and we end up with the Maccabean revolt.
This begins the new era of creating the myth of the great Jewish peoples; from here on there is only Judah and the line between the identity of Israelite and Jew gets more and more blurred until we much later have anthropologists working to sift through the distinction once again that previously existed.
This is where the heaviest push toward monotheism really begins; following the Maccabean revolt; archaeological finds greatly dwindle in artifacts of diversified deities and goddess icons begin their descent (but are not yet entirely absent).
OK, that's the quick once over, but we have to back up because I stated that the 8th c BCE was our earliest point for these Hebrew groups moving toward any form of monotheism and the Maccabees are 700 years following this so clearly there's a gap.
As best as I can tell, from what we have discerned from archaeological and paleographical evidences, it appears that around the 8th c BCE Judah and Israel started feuds of sorts which resulted in textual differences that appeared to result in, at least, some kind of back and forth textual or theocratic contest between Judah and Israel across the 8th and 7th centuries.
Eventually the 6th c BCE happened and both Kingdoms were collapsed.
When recovery from this happened, only Judah was left standing around the middle of the 6th c BCE range - this is also roughly around when suddenly it is quite more pronounced that the Law is now the go-to source of authority and not the ruling Kings (this could be a result of the loss of the original Kingdom of Judah and lack of Kingship being capable of guaranteed retention by their own sovereign peoples).
Either way, this sets off a chain of events which will loop us back to the Maccabean revolt where we really get polarized into a monotheistic fashion (oddly, they result a bit later in the Hasmonean increase of the Hellenistic ingest despite early contest against Hellenist parties) and this movement more or less reaches its highlight with Jonathan gaining leading power and High Priest power at the same time; again an extreme time of civil stress and the move he takes is one of legal survival as in taking the High Priest, the other parties are (technically) no longer permitted to attack him, which had been going on previously according to the writings we have today (we should probably keep in mind that we only have one side of the story).
So, could we understand Judaic Monotheism without the Hellenistic culture?
No; it is intertwined but distinct.
It is not the Hellenistic culture which gave rise to Judaic monotheism, but it is the continued struggle of this group of Hebrew peoples for sovereignty and preserved identity against cultures, which included the Hellenistic culture, which produced their interest in a more unified cultural identity found in monotheistic theocracy.
Oh my, I've ran off at the keyboard again.
Well, I hope I helped in some manner along the winding way.
Cheers,
Jayson