By the time six-time Oscar winner "Mad Max: Fury Road" opens, the world is dead. The "Mad Max" franchise, beginning with the 1979 original movie, takes place in a desolate Australian wasteland where cities have been replaced by infinite stretches of sand. What happened?

The world's oil supplies evaporated, touching off a cataclysmic global war. Although the "Mad Max" films don't have a concrete timeline, director George Miller and the screenwriter for the original film, James McCausland, have revealed that the films exist in a universe where the world implodes in the chaos following complete oil depletion.

Warner Bros.

In 2006, McCausland wrote an op-ed on oil dependence for Australia's Courier-Mail, saying:

George and I wrote the [Mad Max] script based on the thesis that people would do almost anything to keep vehicles moving and the assumption that nations would not consider the huge costs of providing infrastructure for alternative energy until it was too late.

The original script was written in the shadow of the 1973 oil crisis, which had huge political and economic effects following an international oil embargo.

"Mad Max" follows this to its extreme conclusion: economic and societal collapse. In a dark mirror to the 1973 crisis, "Mad Max" takes place in a world where oil scarcity, instead of recovering eventually, sets off a chain reaction of war, destruction, and the nuclear apocalypse.

In this still from the 1979 original film, you can see that the world isn't yet the barren wasteland seen in "Fury Road." Youtube/Warner Bros.

The opening moments of the second film, "Mad Max 2" — aka "The Road Warrior" — lays out how everything fell apart. The narrator recalls a time "When the world was powered by the black fuel and the deserts spouted great cities of pipe and steel. Gone now, swept away ... without fuel they were nothing."

In time, the economic collapse destabilized entire cities. This touched off a bloody civil war over resources, leaving only disorganized bands of scavengers willing to kill to survive.

"Their leaders talked and talked and talked, but nothing could stem the avalanche, their world crumbled, cities exploded, a whirlwind of looting, a firestorm of fear, men began to feed on men," the narration of continues.

In a key scene during the third film, 1985's "Mad Max Beyond Thunderdome," Max is told the final part of the story. In a desperate grab to secure the last reserves of oil, the world was drawn into a nuclear war that decimated the remaining natural resources. The world was dead.

The cave paintings from the third film detail the nuclear war. Max is depicted in the cave painting as well. YouTube/Warner Bros.

When "Fury Road" begins, all known remaining resources — clean water, functioning vehicles and weapons, and viable oil — have been hoarded by one man: Immortan Joe. He leads The Citadel, where he's worshipped as a living god. Max finds himself wrapped up in the battle to overthrow him, pursued by Immortan Joe across the desert wastes that used to be Australia.

Immortan Joe. Warner Bros./"Mad Max: Fury Road"

Despite minimal dialogue, the franchise features smart and insightful social commentary, best summarized by "Fury Road's" costume designer, Jenny Beavan, during her Academy Award acceptance speech for best costume design.

"It could be horribly prophetic, 'Mad Max,' if we're not kinder to each other, and if we don't stop polluting our atmosphere, so you know, it could happen," she said.