For the timeline attached to the rebooted franchise starring Tom Hardy, see Timeline of events (rebooted franchise).
This timeline has been assembled from various interviews with the creators of the movies, official documents & other legitimate sources. Movies themselves provide very little backstory and concrete information as to what exactly triggered the events leading up to the apocalypse. The first movie gives almost no exposition except for the opening line "A few years from now". The sequel provides a vague description of events that led to the apocalypse, not detailed enough to determine when it happened and who was responsible for it. The third movie shows a bit more of the backstory but again, it is rudimentary. The entire Mad Max trilogy does not explicitly provide any dates except for two hidden ones in Mad Max and one partially obscured in Mad Max: Beyond Thunderdome. The dates are as follows (in order of appearance):
- December 6th, 1984 written on the Highway 9 Sector 26 sign
- "est. 1983" seen on the MFP plate at the gates of Halls Of Justice (not visible in the movie, info retrieved from a movie prop)
Mad Max: Beyond Thunderdome:
- September 10th 199?: the day Captain Walker left The Crack In The Earth along with other adults from the crashed Boeing 747 in search of civilization. In the script, this date was originally November 8th, 2005.
George Miller revealed in an interview  from 1984 that the events of the first two movies took place some odd 15 years from then. This would place the first two movies in the mid to late 90's. Mad Max Beyond Thunderdome takes place 15-18 years after which puts it in 2014 - 2018.
However, according to the dates provided by production documents and movies themselves, the original trilogy starts in mid 80's and ends in 2005.
The Persian Gulf War (Pre-Mad Max)
"Law and order, like every other aspect of the Western society have been swept away - put to the torch one early morning when Iranian troops trying to export revolution, struck deep into the heart of Saudi Arabia". 
The war between Iran and Saudi Arabia left the Persian Gulf devastated in just two days. The oil fields were set ablaze and oil export halted almost immediately. Prices of oil doubled, then quadrupled and quadrupled again. North West and Trans-Persian pipelines have been destroyed shortly after. The West's seven biggest oil companies led by Exxon (The 7 Sisters Petroleum - as seen on the tanker in Mad Max 2) have immediately announced they will not fulfill their supply contracts.
Impact on Australia
The price of gold skyrocketed along with the inflation. In an attempt to save the economy and conserve fuel - martial laws have been announced all across the world. Italy and Spain have been taken over by the military. The Australian economy collapsed, companies filed bankruptcy one after another. Massive lay-offs caused the heavy industry to shut down. In Sydney & Melbourne panic turned into riots. People tried to withdraw savings from banks only to see the bank doors nailed shut. Gas stations were sucked dry by people fighting over last drops of gasoline. Ordinary citizens began to arm themselves. The Outback was slowly taken over by bike gangs. The remaining oil tankers were under constant attack. Vehicles that ran out of fuel were abandoned on the roads. Intercity communication stopped.
Main Force Patrol (MFP) was formed as the last-ditch attempt to uphold the law on the roads. Max Rockatansky was one of the best drivers in the MFP. He went rogue after his friend and family were killed by a biker gang.
Further decay (Pre-Mad Max 2)
Coal & fuel powered generators ground to a halt causing the lights to go out. All electrical appliances stopped working. Suddenly food became a precious commodity. Looting became common by day, preying on the weak common by night. It had become obvious that the weak would perish and the strong would survive. As a result, lone scavengers began to form gangs that roamed the Wasteland in their home-made dune buggies and bikes. 
People were fleeing the cities. Papagallo - a former oil company employee - took maps leading to the Compound and headed there along with the others. Max wandered out into the Wastelands. Lord Humungus - a former military member whose face had been disfigured in an accident formed a gang along with Wez - a Vietnam vet. His gang bolstered their forces through the recruitment of lone scavengers, some of which with a military background.
Mad Max 2
Three years after the events in Mad Max the society was in complete decay, the economy was nonexistent, people had fled out into the Wastelands for safety only to find that Marauders were roaming there for fuel and resources.
Nuclear apocalypse (Post-Mad Max2)After the economy collapsed and the fabric of society disintegrated all across the world, the remaining governments were still trying to secure the last oil resources. This had led to a global nuclear exchange. It is unknown who struck first, but everyone had suffered. Nuclear winter followed shortly after. The pilot Captain Walker tried to take people out to safety from Sydney onboard of a Boeing 747 . The plane had crashed due to turbulence and the remaining survivors formed a tribe. The climate changed once again, it became dry and hot, deserts started to form.
Mad Max Beyond Thunderdome
15 years after the events of Mad Max 2, the society as we know it no longer exists. The only remaining shreds of civilization either live off of the old world or decide to start over again. Water is scarce & radioactive. The landscape had been turned into a desert. Oil is no longer.
- ↑ http://www.omnimagonline.com/omni_book-ScreenFlights_Fantasies.html
- ↑ http://madmax.wikia.com/wiki/File:Mad-max-2-synopsis-page-1.jpg
- ↑ http://madmax.wikia.com/wiki/File:Mad-max-2-synopsis-page-3.jpg
- ↑ http://www.scifiscripts.com/scripts/madmax2.txt
- ↑ http://madmax.wikia.com/wiki/File:George_Miller_Interview_1984.jpg