Create some conflict between the character hearing it and the character telling it.
Don't just infodump the history. The exact nature of the conflict depends upon the relationship of the characters; but make the character hearing it question the decisions, the motives, ask questions to clarify setting or who is who. This could be two people on a first or second date, a conversation on a trip (plane, train, hike to another town in a less technological setting), or an expert trying to understand the history (a doctor, or mercenary).
If Alice is trying to tell Brie her story, Brie should not be a passive receptacle, oohing and ahhing and nodding and wincing and sympathizing. That might be how real life unfolds, but it is boring fiction.
Brie should be actively trying to understand the relationships in Alice's story, even arguing about the details or the motivations of the characters or why they knew what they did or did what they did, or arguing about her memory of the sequence of events in some part of the story.
In some way you need a challenging listener. This doesn't have to be hostile (it could be, in an argument, or a conversation with somebody that doesn't really want to hear the history), it can be a friend: "That is the stupidest thing I ever heard, what in the world were you thinking?"
It can be a person averse to the emotions in the story: A judge, a lawyer, a doctor, a police detective, a cop.
Infodumps (of any kind) tend to be boring, You can defeat the boredom by adding conflict, which turns your "history lesson" into a present-day conversation / argument that isn't boring. It may be twice as long, but the conflict is what it takes to hold the reader's interest.
My secondary advice would be to not meander too much in this history with irrelevant detail; a challenging listener can help with that. One way to "tighten" a story is to limit what we tell readers to things that will have, or have had, consequences that influence the tale. That is not an ironclad rule for me, I like describing scenes with details that won't matter to the plot, but I think are entertaining.
But in your case, if you are worried about the length of this history, tighten it up to just what is necessary without frills, add emotion to the speaker with a challenging and not-too-sympathetic or solicitous listener.