I deliberately chose a broad region to enable a wide variety of possible answers. I know that one possible reason for the fall of the large kingdoms of the bronze age is that iron enabled poorer people to make weapons, which disrupted the structures of power.
While iron is widespread, it seems likely that it took a while for knowledge of how to mine and forge it to spread. Was lack of basic metal tools a problem?
This notion that iron was a metal "of the people" that disrupted Bronze-Age power structures is new to me. I'm not dismissing it outright, but I would like to see some convincing evidence. After working extensively with "Dark Age" (ie Early Iron Age) Greek topics, I can say with great confidence that the evidence for "Greece" (ie the Balkans, the Aegean, Asia Minor, and the Greek colonial horizon in Sicily) in fact points to the opposite: that iron implements in the Iron Age and even down into the early Archaic period were precious objects and symbols of elite prestige in their own right. From your date of 1000 BCE down to 650 BCE, we overwhelmingly find iron objects in two distinct contexts, and virtually nowhere else in any quantity:
Elite graves, often called "warrior graves" to align them with similar such burials in Near Eastern, North African, and Continental peoples of similar time period and circumstances. Such graves in Greece, from the 10th to about the 8th century, very often contain "killed" iron or bronze weapons, ritually bent and deposited in the grave as a symbol of elite status. They are invariably accompanied with other objects announcing elite status, like imported exotica (faience beads, Near Eastern gold jewelry, amber, etc) and painted fineware pottery, some of it ritually destroyed and burned on the pyre along with the deceased before being deposited. The classic example of such a grave is the "Big Man" buried under the Toumba tumulus building at Lefkandi, though there are many hundreds if not thousands of other examples from Attica, the Corinthia, Lakonia, the Argolid, Crete, and the Aegean.
Around the middle of the 8th century, we see that metal objects begin to disappear from graves in Greece. At the same time, we see an intensification of deposition of metal at sanctuaries, particularly sanctuaries where multiple different communities came together (like Olympia, Delphi, Isthmia, Perachora, the Argive Heraion, etc.). It is clear that the display of elite status through the deposition of metal objects in graves is no longer in fashion or socially acceptable, and that conspicuous disposal has shifted to sanctuary dedications.
This is all discussed in masterful, approachable prose by the venerable Robin Osborne in his Greece in the Making (link), which I very highly recommend if you are at all interested in this topic. It is probably available used all over the place and affordable.