It’s a bit optimistic to call the study of Bronze Age Greece ‘ancient history.’ It’s closer to archeology.
There is some myth, but can the Illiad be considered historical record? Even though the Trojan war probably did happen in some fashion, does Homeric myth count as record?
If not, how do we know things? Digs. Submerged records. Artifacts in tombs or shipwrecks. All of which are more archeology than history.
It’s in the shadow area when we really make changes to what we know. Outside history, we know the mechanisms of how people lived. We know their weapons, their diets, and their extent. We know nothing of their doings, their politics, or their cultures. We don’t know what songs proto-man sang even if we know the tonal range by bone analysis. We don’t know when they feasted or for what even though we know what they ate.
And on the other side of the shadow are is true history. We know the actions of Roman people. We’ve read their campaign posters, seen their party pictures, followed their wars, foreign policies, and domestic politics via personal accounts, correspondence, and histories told by others long after. We have the billing statements for the legion budget. We know their jokes, their songs, and their artistic movements. We know so incredibly much more than what we know archeologically.
And the Illiad dwells in the shadow area. So does 800-ish to 1200-ish Scandinavian history and myth. We think a Trojan War probably happened 1187BC-ish. We think a Fimbulwinter probably occurred in 987-ish AD. Two thousand years difference, and yet both in the shadow area of myth. The Three Kingdoms period of China is born in here but escapes by its end. We know almost nothing of the Apache, the Navajo, and so many other tribes from before Europeans arrived. There is almost no shadow, merely a sudden darkness as one goes back from winner written rules to nothing left.