1200 to 800 BC, a ****lot of years, aka the Dark Ages of Ancient Greece

The chaotic times of 1200-1000 BC left many Greek city-states depressed and dilapidated. Most of the people who survived went through grueling ordeals and poverty. We know very little about this time of disaster and the period of recovery that followed, because only a scanty body of literary and documentary documents exists to supplement the scanty information now available to archaeology. Partly because conditions were too dark and brutal for too many people, and partly because we have such a vague picture of what happened, historians refer to the period from the 12th and 11th centuries BC as the Dark Ages (and here I wonder why it is "from the 12th and 11th centuries BC" and not just the 12th century). Why not just say the 12th century? The Greeks did not recover until 750 BC. (In contrast, the Near East recovered faster, ending their Dark Ages around 900 BC)

The Dark Ages of ancient Greece lasted about 300 years,

Long before the rise of ancient Greek civilization, about 800 years ago, the Aegean region gave birth to the brilliant Cretan and Mycenaean civilizations. Around 1200 BC, the invasion of another group of Greeks (the Dorians) destroyed the Mycenaean civilization, and for the next 300 years, Greece fell into a state of complete silence, closed and impoverished, and the history of Greece entered into the so-called "Dark Ages". This period is also known as the "Homeric Age" because it is mainly known from the Homeric poems. Towards the end of the Homeric period, iron tools were popularized and replaced bronze tools. Maritime trade was re-developed and new city-states were established. The Greeks created their own script using the Phoenician alphabet and held the first Olympic Games in 776 BC. The convening of the Olympic Games also marked the beginning of a period of prosperity for ancient Greek civilization. Around 750 B.C., the Greeks began to colonize as their population grew. Over the next 250 years, new Greek city-states spread along the Mediterranean coast, including Asia Minor and North Africa. Among the city-states, the most powerful were Sparta and Athens.

Is this clear enough?