Answer:
The mask was made 300 years before his death
Step-by-step explanation:
Historians know that the mask of Agamemnon is not actually from the famed Mycenaean king because the graves where it was found was before the Trojan War by 300 years.
"German archaeologist Heinrich Schliemann, who discovered the artifact in 1876, believed that he had found the body of the Mycenaean king Agamemnon, leader of the Achaeans in Homer’s epic of the Trojan War, the Iliad, but modern archaeological research suggests that the mask dates to about 1600 BC, predating the period of the legendary Trojan War by about 400 years."