Marvel's Dark Reign narrative was one of the most memorable runs in the comic book company's history, partially because it arguably marked the end of a key Marvel strategy. Throughout Marvel's history, there have been multiple eras which define a period of time for the comic book company. While the eras were often used as a marketing strategy, they usually incorporated a narrative atmosphere that impacted the character's storylines. These time periods were often launched through major events that would have a long-term impact on a huge range of comic runs.
Source：https://www.cbr.com/dark-reign-norman-osborn-last-great-marvel-comics-era/
