The decline of the Bronze Age led to the beginning of the Iron Age. Bronze was dependent on functioning trade networks: tin was only available in large quantities from mines in what is today Afghanistan, so the collapse of long-distance trade made bronze impossible to manufacture. Iron, however, is a useful metal by itself without the need of alloys (although early forms of steel - iron alloyed with carbon, which is readily available everywhere - were around almost from the start of the Iron Age itself). Without copper and tin available, some innovative smiths figured out that it was possible, through a complicated process of forging, to create iron implements that were hard and durable. Iron was available in various places throughout the Middle East and Mediterranean regions, so it did not require long-distance trade as bronze had. The Iron Age thus began around 1100 BCE, right as the Bronze Age ended.
One cautionary note in discussing this shift: iron was very difficult to work with compared to bronze, and its use spread slowly. For example, while iron use became increasingly common starting in about 1100 BCE, the later Egyptian kingdoms did not use large amounts of iron tools until the seventh century BCE, a full five centuries after the Iron Age itself began. Likewise, it took a long time for “weaponized” iron to be available, since making iron weapons and armor that were hard enough to endure battle conditions took a long time. Once trade networks recovered, bronze weapons were still the norm in societies that used iron tools in other ways for many centuries.
Outside of Greece, which suffered its long “dark age” following the collapse of the Bronze Age, a number of prosperous societies and states emerged relatively quickly at the start of the Iron Age. They re-established trade routes and initiated a new phase of Middle Eastern politics that eventually led to the largest empires the world had yet seen.