Billions of years ago
A mysterious mechanoid race, calling themselves the "Creators," continually tried to create life throughout the universe.
The "Creators" used a type of molecular weapon to transform the surfaces of planets that harbored organic life, converting those organisms into "Transformium": a special metal that could be used to create and repair silicon-based life forms.
Using the collected "Transformium," the Creators made the planet Cybertron and soon developed the "Cube" to power it, creating a race of sentient mechanical beings there. These beings called themselves Cybertronians and regarded the "Cube" as a sacred object of their creation, naming it the "Allspark."
Among all Cybertronians created by the "Allspark," the first born seven "Primes" joined forces to establish the "Dynasty of Primes," unifying the entire Cybertron.
Unlike their descendants, the seven "Primes" did not have the ability to transform, but because they were directly created by the "Cube," their abilities far exceeded other Cybertronians.

4 billion years ago
Before constructing Cybertron, the "Creators" also experimentally built another giant mechanical metal planet, which, due to a failed experiment, became self-aware - later known as "Unicron."
In the early days of the "Dynasty of Primes," there were continuous battles against "Unicron," and in the end, with the power of the "Allspark," the seven "Primes" defeated "Unicron" and isolated its consciousness, pushing its body to the edge of the galaxy. "Unicron" later fell into the gravitational pull of a star, orbiting it stably, with interstellar matter gradually wrapping around its body to form a new planet - Earth.

65 million years ago
The "Creators" visited the solar system, using molecular weapons on Earth's surface to create a large amount of "Transformium." During this process, one of the "Creators," the "Quintessa," also used the energy of the sun to create another batch of silicon-based life forms, which could mimic dinosaurs on Earth and transform at will. Some of them became the later "Dinobots," while others were selected as Quintessa's guardians, the "Knights of Iacon."

60 million years ago
The "Allspark" had expended much of its energy after creating the seven "Primes," so the later Cybertronians were not created using the "Allspark." The "Dynasty of Primes," through reverse engineering the "Allspark," developed a substance called "Energon" that could achieve a similar effect to creating mechanical life but required energy on a stellar level to produce.
The rule of the "Dynasty of Primes" on Cybertron stabilized, and due to the enormous stability of silicon-based life, the planet's population began to increase sharply. The seven "Ancestors" started considering expanding their dynasty's territory to other star systems.
Creating "Energon" required large-scale collection of stellar energy, a process that could cause the core of the star to wither, so the seven "Primes" unanimously agreed not to extract stellar energy from any star systems where life had already appeared.

25,000 years ago
One of the seven "Primes," "Megatronus Prime," believed he was the chosen one and became dissatisfied with his six brothers' conservative expansion policy. He felt there was no reason to waste time on those primitive and backward carbon-based life forms; all stars Cybertron could utilize should be "harvested."
Thus, "Megatronus Prime" began to quietly recruit those within the dynasty who shared his ideology, calling them "Decepticons," with his most trusted being "Jetfire" and "Megatron."

"Jetfire"
"Jetfire" found for "Megatronus Prime" a large number of stars that could be "harvested." Although many of these star systems harbored life, "Megatronus Prime" did not care and claimed within the dynasty that these star systems had no life. They then wantonly harvested the energy of the stars, leading to the extinction of a large number of lives.

17,000 years ago
In this period, "Megatronus Prime" continuously expanded his and the "Decepticons'" power, reaching a level where they could contend with the "Dynasty of Primes." They began to openly build the "Star Harvester" on Earth, attempting to absorb the energy of the sun to continue building their arsenal. "Megatronus Prime" hoped to force the other six "Primes" to appear on Earth to stop his plan, falling into the trap set by the "Decepticons" and eliminating the leaders of the "Dynasty of Primes."

"Star Harvester"
However, the repeated extinction of lives caused "Jetfire" to fall into remorse, ultimately leading him to betray "Megatronus Prime" and the "Decepticons." This plan was leaked by "Jetfire," and although it allowed the six "Primes" to avoid immediate danger, they were still no match for the greatly strengthened "Megatronus Prime." As they were about to be eliminated by "Megatronus Prime" one by one, the "Primes" chose to sacrifice their lives, sealing the key to activating the "Star Harvester" - the "Matrix of Leadership" - in a secret location on Earth, and imprisoning "Megatronus Prime" in a dimensionally isolated sarcophagus.

17,000-11,000 years ago
The sudden disappearance of the seven "Primes" led to a severe civil war on Cybertron, with various factions fighting each other for the limited "Energon." Among these factions, the "Decepticons" were the most powerful and most likely to reunify Cybertron. Still, the fact that "Megatronus Prime" betrayed the "Dynasty of Primes" also led many smaller factions to gradually unite and form the "Autobots." Under the leadership of two descendants of the "Primes," Sentinel Prime and Optimus Prime, they resisted the rule of the "Decepticons."

11,000 years ago
After years of civil war, the "Autobots" were still inferior in strength to the "Decepticons." To prevent their opponents from getting the "Allspark," Optimus Prime, the former science advisor of Cybertron, had no choice but to launch the "Cube" into deep space.
At this time, the retreating "Autobots" were unable to resist the "Decepticons'" attacks. Cybertron was ravaged by war. Sentinel Prime believed that if their race were to survive, they needed to find a new path. Thus, he decided to inform Megatron of the "Cube's" whereabouts and secretly agreed to meet on Earth to discuss the future of Cybertron.
Unexpectedly, while en route to Earth on the "Ark," Sentinel Prime was attacked by the "Decepticons" who were unaware of the plan, its faster-than-light engine was destroyed, causing the "Ark" to drift aimlessly at low speed.

10,000 years ago
Around 10,000 BC, the "Cube" fell into Earth's atmosphere. Megatron, who followed the Cube, was hit by a meteorite causing him to go off course and crash in the Arctic. Megatron's consciousness was disrupted by the impact, and he was frozen under the polar ice for a long time.

8,000 years ago
Although the "Decepticons" ultimately won the war, Cybertron had become uninhabitable due to the conflict. Most of them chose to flee to other star systems and live in exile.

7,500 years ago
As the creators of Cybertron, the "Creators" were not satisfied with this batch of "experimental products," considering them as barbaric and no different from organic life forms. Most of the "Creators" decided to abandon Cybertron and move on to the next creation experiment. Only "Quintessa" believed that Cybertron was still worth saving.
Thus, Quintessa stayed behind to continue the experiment. She awakened the "Knights of Iacon" that she had created on Earth earlier to serve as her guardians, helping her implement the plan to revive Cybertron.

6,000 BC
The "Knights of Iacon" learned of Quintessa's plan to absorb the energy of "Unicron" and transfer it to Cybertron to reactivate the planet's core, which would also completely destroy Earth.
Born on Earth, the "Knights of Iacon" decided to betray their creator, stealing Quintessa's staff and hiding it secretly on Earth.

500 BC
A young human named Merlin accidentally entered the temple of the "Knights of Iacon." He reached an agreement with these giant intelligent machines to keep their secret in exchange for their assistance when needed to perform "miracles."
Years later, Merlin used the power of the "Knights of Iacon" to help King Arthur repel the Saxon invasion, earning the knights' trust and becoming the guardian of "Quintessa's Staff."
Because "Quintessa's Staff" was encoded with Merlin's DNA, only he and his descendants could use it, leading Merlin to create the "Order of Witwiccans" to protect the secrets of the Cybertronians on Earth.

1897
Archibald Witwicky, a member of the "Order of Witwiccans" and a polar explorer, discovered the crash site of Megatron in the Arctic Circle and "accidentally" activated his navigation system, imprinting the coordinates of the "Cube" on his glasses.

1913
The "Cube" was discovered upstream of the Colorado River in North America. In response to this significant discovery, the U.S. government established "Sector Seven" to conduct research related to it.

1934
The crash site of Megatron was secretly excavated by Sector Seven, who then designated him as "NBE-1" (Non-Biological Extraterrestrial), and transported him in cryostasis to a research base beneath the Hoover Dam. Reverse-engineering research on "NBE-1" sparked the information revolution, greatly accelerating human technological progress.

1961
Human deep-space probes detected a crashed alien spacecraft on the far side of the moon (Sentinel Prime's Ark). President Kennedy's team believed this spacecraft was likely related to "NBE-1" discovered by Sector Seven, hence legislation was signed to initiate the Apollo program, aiming to send humans to the moon to investigate as soon as possible, triggering a space arms race between the USA and the USSR.
Armstrong discovered several dead "NBEs" inside the Ark, unaware that one was still alive, in a deep sleep within the lower bays of the ship.

1986
Following in the footsteps of the American moon landing, the Soviet space agency also found the Ark on the moon. They successfully brought back parts of the ship's engine and an energy cell for technical research, but this cell exploded at a facility in Ukraine, causing the Chernobyl nuclear disaster.

2007
The fallen "The Fallen" (Megatronus Prime) escaped from his sarcophagus prison, believing Optimus Prime would likely send the "Allspark" to Earth, thus summoning the Decepticons to infiltrate Earth and investigate Megatron's whereabouts. Utilizing data collected by Frenzy through the communication network of Air Force One, the Decepticons discovered critical information regarding Archibald Witwicky and "NBE-1."
Meanwhile, Sam Witwicky, the great-grandson of Archibald Witwicky, unwittingly purchased an old Chevrolet Camaro, which was actually Bumblebee in disguise. With Bumblebee's help, Sam evaded capture by the Decepticons and decided to help the Autobots locate the "Allspark."
Sector Seven's facility holding "NBE-1" was compromised, Megatron awoke from his frozen state, led Decepticons in preparation to seize the "Allspark," planning to use its energy to transform Earth's mechanical surrogates into life forms and rule this new world. Although the Autobots rushed to assist under the command of Optimus Prime, they couldn't withstand the Decepticons' assault. In a critical moment, Sam shoved the "Allspark" into Megatron's chest, using its energy to destroy his core but also shattered the "Cube" into many pieces.

2009
Megatron's failure on Earth made The Fallen realize not to underestimate the strength of humans and Autobots. While gathering strength, he summoned Decepticons scattered across other star systems.
Meanwhile, Soundwave, through a spy satellite, located Megatron's body and remnants of the "Allspark." The remaining Decepticons stole the last piece of the "Allspark" and used it to revive Megatron.
Under The Fallen's guidance, Megatron and his followers decided to reactivate the Star Harvester hidden within the pyramids to absorb the sun's energy and mass-produce Energon, but this plan was thwarted by the alliance of humans and Autobots. Ultimately, even with The Fallen's personal involvement, he was defeated by Optimus Prime, reborn using the "Matrix of Leadership."
Seeing the tide was against him, Megatron was persuaded by Starscream to abandon the attack and temporarily retreated to seclusion in the deserts of Africa.

2012
Autobots and N.E.S.T. discovered components left by the Ark during investigations in Chernobyl, revealing that humans had long been aware of a crashed alien ship on the moon.
Optimus Prime was extremely dissatisfied with humanity's concealment of this critical information, personally went to the moon and brought back Sentinel Prime, who was in deep stasis. However, the awakened Sentinel Prime quickly turned traitor, killing Ironhide and stealing the Energon cell under Autobot control.
The so-called "Energon cells" were the activation devices for the Space Bridge developed by Sentinel Prime, allowing objects to be remotely transported to the location of the Energon cell. Sentinel Prime had conspired with Megatron thousands of years ago, planning to transport Cybertron to Earth's location, using the sun's energy to revitalize the dying Cybertron.
The human enterprise Accuretta Systems, already infiltrated by the Decepticons, deployed all Energon cells within Chicago's city limits. However, when the transport was halfway, Optimus interrupted it, causing Cybertron's celestial body to be severely torn apart, becoming a dead planet.
Sentinel Prime gained the upper hand in the subsequent one-on-one confrontation with Optimus but was betrayed by Megatron. The escaping Optimus finally destroyed both Megatron and mournfully killed his gravely wounded former mentor Sentinel Prime.

2012-2017
Following the "Chicago Incident," the U.S. government stopped trusting any Cybertronian, and the newly established anti-alien task force, "Cemetery Wind," began hunting down Decepticons as well as secretly targeting the Autobots. Survivors like Optimus Prime and Bumblebee were forced into hiding.
Seeing Cybertron, which she created, had become a dead planet, Quintessa decided to initiate her planet revival plan. She slowly moved Cybertron towards the solar system while hiring Lockdown, who remained neutral during the civil war, to capture Optimus Prime and bring the only surviving Prime back to Cybertron to face their Creators.
Lockdown allied with the technology company KSI, exploiting the company's greed to produce "man-made Transformers" on the condition that they help capture Optimus Prime. KSI used the deceased Megatron to create a more powerful "Galvatron," unaware that it was Megatron's consciousness using KSI to create a new body for himself.
The reborn Galvatron planned to use the "Seed," a molecular weapon left by Lockdown, to convert Earth's organic beings into Transformium. This time, however, Optimus received the aid of the ancient Dinobots and once again foiled the plans of Megatron/Galvatron.
Lockdown, intending to personally bring Optimus back to Cybertron, was killed by Bumblebee and Optimus working together.
After this battle, Optimus decided to take the "Seed" back to Cybertron to question the Creators' true intentions.

2022
After consecutive Cybertronian invasions, "Unicron," the core of the Earth, showed signs of awakening, with colossal horns appearing around the world and growing in size.
Optimus Prime, who traveled to Cybertron to confront the Creators, was immediately subdued and brainwashed by Quintessa, transforming him into the fallen warrior "Nemesis Prime."
Nemesis Prime was sent back to Earth to find “Quintessa's Staff,” which Quintessa intended to connect to an anchor point beneath Stonehenge, draining Unicron's/Earth's energy.
Viviane Wembley learned she was the last living descendant of Merlin. With the help of the Autobots, she located Merlin's tomb. However, Nemesis Prime emerged, attempting to seize Quintessa's Staff. Bumblebee, using his original voice, caused Optimus's consciousness to resurface.
Galvatron seized the opportunity of Autobot infighting and took the staff to activate Unicron's anchor point, allowing Cybertron, now orbiting Earth, to absorb the released energy.
At the same time, Cybertron, pushed by Quintessa into Earth's orbit, collided with Earth, causing millions of deaths. However, with the protection of the human military and Autobots, Viviane entered Cybertron's ignition chamber, removed the staff from the anchor point, and stopped Quintessa's plan.
Although Earth's core was no longer at risk of withering, Unicron still posed the potential to reawaken. Optimus Prime and the Autobots decided to go to Cybertron, now in a synchronous orbit with Earth, to attempt repairing the planetary core and prepare for Unicron's possible return.
On Earth, the surviving Quintessa, disguised as a human, continued executing her plan.