We all heard about the Bronze Age collapse, which was a mysterious time him history due to a lack of good research.
We were all baffled about what caused the collapse of the Bronze Age civilizations, so much so that we seem to forget how the world recovered from the Bronze Age collapse.
How did Homer learn to write the Iliad and the Odyssey if the Greeks forgot how to write?
How did the Greeks rebuild the cities if they fled them into the mountains and the countrysides?
I assume that there were people who remembered how to build cities and write but the Greek Dark Ages were from 1,100 BC to 750 BC, which is a whopping 350 years, making this seem unlikely.
One other possible assumption is that Cyrus The Great expanded his empire close enough to Greece that it taught them how to write and how to build cities. The Persian civilization didn't go through the Bronze Age collapse so we could assume they learned how to write and build cities, but it is unlikely that the Greeks will be able to learn from the Persians this fast to resist the first Persian invasions, 50 years later.
OK. There's a lot to unpack here.
There is a basic flaw in your statement. You seem to think that there was a complete and total collapse everywhere. There wasn't.
Start with Homer and writing. Greeks lost their version of writing. But, they were not the only groups that had writing. Writing as a concept existed throughout the whole of the eastern Mediterranean Sea region and Mesopotamia. The writing system the Greeks used during Homer's time were heavily influenced by the Phoenician writing system, which in turn was derived from the Canaanite/Semitic system used prior to the Phoenician culture's arrival in the Levant. Then, the Canaanite/Semitic alphabet was influenced heavily by earlier Egyptian writing systems. All of the latter writing systems combined showed continuity from prior to the Bronze Age collapse to well into Classical Greek times, even if individual writing systems might not span the whole timeframe.
Same applies to cities and other items. There were actually large numbers of cities founded and built in the regions around the Mediterranean Sea region and Mesopotamia after the Bronze Age collapse.
There was never a complete break in technology or civilization as a concept. There were regional regressions, but multiple avenues for the reintroduction of those concepts as well as the specific technologies.
Phoenicians and other societies traded throughout the entire region through the centuries between 1177BC and the arise of the Persian Empire. There were Greek colonies in the 7th and 8th Centuries in Sicily and Southern Italy, which brought them into contact with the Etruscans and Romans and their cultures and technologies. (I use the term somewhat loosely in relation to the Romans for that specific era). The Phoenicians were building cities in the same regions that the Greeks were colonizing at roughly the same time. Ionian Greeks colonized Anatolia starting about the year 1000. But, of importance here, the Greeks and Phoenicians were in contact in the same areas during the timeframe that the Greeks adopted a new writing system.
Basically, the phrase "Bronze Age Collapse" refers to specific empires and their collapse. It does not reflect a universal collapse in that aftermath. Arguably, there were regions that benefitted from the collapse. Technology never stopped everywhere. Writing never stopped everywhere.
u/shemanese did a good job tackling the bones of your questions, but I want to add some details about how the Bronze Age collapse impacted the Near East, especially in regard to the Persians.
Many historians/archaeologists now make the argument that the Bronze Age Collapse was mostly an economic disaster where some areas were affected more than others. Obviously you've already discussed the massive social decline experienced by the Greeks. Other regions, like the Hittite kingdom in Anatolia saw extensive decline and loss of a central government, still more like Assyria and Babylon saw their territory reduced to just the core cities of their kingdom. Even though we know most of our information about the so-called "Sea Peoples" from Egypt, they actually seem to have weathered the storm quite well, fractured and compressed into their traditional borders, but not suffering the same loss of territory or total cultural collapse seen by their neighbors.
This also didn't happen all at once. While Mycenean Greece collapsed around 1200, and Egypt started waning a couple decades later, the Mesopotamian kingdoms continued to rule large territories until around the 1020s BCE. By 911 BCE, just 100 years later, Assyria was engaged in wars of expansion again, which brought a large central government back into the power vacuum brought on by the collapse a century earlier.
Which brings me to the Persians. The Persians did not suffer in the Bronze Age Collapse, at least not directly, because they weren't in the region we know as Persia yet. At that time, southwestern Iran was ruled by the Elamites. Elam is not usually included in the Bronze Age Collapse narrative, but c. 1100 BCE is the start of a sort of Dark Age for Elamite sources. It seems like there was still a central government, but possibly more than one competing faction. By the early 9th century they were organized enough to be forming alliances with Babylon against Assyria, but up to that point the internal events of Elam are obscure for about 200 years.
It was probably in that same time frame that the Elamites first came into contact with people who spoke Iranian languages, migrating into western Iran from the northeast and settling in the Zagros Mountains. The first of these groups that can be identified from Assyrian records are the Medes in the 9th century, with a group who may be the Persians living well north of "Persia" (modern Fars province) about a century later.
The arrival of the early Iranians in the region was probably the tail end of an ongoing series of Indo-Iranian migrations that started around 1800 BCE, but this particular wave of new arrivals in the Zagros mountains also coincides with other semi-nomadic people migrating into the Near East. The Phrygians suddenly poured into Anatolia - traditionally from southeastern Europe - around 1180 BCE and Arameans pushed into Mesopotamia from Syria around 1100 BCE. There has been some speculation that the initial decline in trade, possibly coupled with climate change, sent these nomadic groups into more settled areas, further destabilizing each region.
So the very earliest hints of a Persian tribe - not yet in Persia - appeared in the 8th century BCE, around the same time the works of Homer and Hesiod are supposed to have been written. The Elamite kingdom would not fall, and finally be replaced with a small Persian kingdom until some time after 646 BCE, and Cyrus the Great did not initiate his conquests until 553 BCE, almost 200 years after Greece started writing again.
The other two answers did a wonderful job unpacking most of your question! I can add a bit about your specific example on Homer. The Iliad and the Odyssey (and the other epic poems of the time) were part of an oral tradition. While attributed to a specific author (Homer), really each poet had their own version depending on where and when they were reciting the poem. So what we currently have as the “official” texts of both of those poems is a long line of personal edits and translation choices that have ultimately shaped the stories greatly. We have no evidence of Homer writing down these poems, he wouldn’t have needed to since they were a part of the oral tradition of the time.