Freeza's Force-Saiyan conflict
From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
Genocide of the Saiyans is the name given to the very brief, but incredibly disastrous conflict, between Freeza's Force and the Saiyans.
Main article: Dragon Ball Z: Bardock: The Father of Goku
After receiving word from Zarbon that a band of low-class Saiyans had successfully conquered Planet Kanassa, a mission stated by Dodoria to be so difficult that even elite squadrons of soldiers had not even bothered attempting it, Frieza was in utter disbelief. Initially, Frieza realized that no Saiyan alive at the time would be any sort of threat to him or his vast empire, but contemplated on the fact that the Saiyans power was quickly growing, and sometime in the near future, a Saiyan warrior may arise that could possibly challenge his might, especially if the Super Saiyan legend was evidently true. Frieza soon ordered the Saiyan squad responsible for the Kanassan war victory to be given another assignment, one that would be used as a distraction for a deadly ambush.
Meanwhile, during Bardock's recovery, King Vegeta learned from his scientists that a Saiyan was born the day before with a power level of ten thousand, possibly making him the Legendary Super Saiyan. King Vegeta, fearing the threat that the baby, named Broly, may possess towards the Royal Family, orders for his execution. Paragus, Broly's father, intervenes and tries to reason to King Vegeta to spare Broly, and tries to convince him that Broly might prove to be a beneficial soldier to the Royal Family. The King tells Paragus that even if that possibility is to be considered, the possibility of Broly overthrowing the Royal Family is true as well. King Vegeta then attempts to execute Paragus for disallegiance and fires an energy beam at Paragus, severely wounding him. Meanwhile, one of Vegeta's guards enters the infirmary, picks up Broly, and stabs him in the stomach. The guards then throw Broly and his father, Paragus into a wasteland to ensure that they die.
While still in recovery from his injuries sustained on Kanassa, Bardock, a Saiyan warrior and father of Kakarrot (Goku) and Raditz, began to have psychic visions of the future after receiving said powers from a Kanassan warrior named Toolo. After seeing visions of Planet Vegeta's destruction and his son growing up on another planet, Bardock realized something was very wrong. After waking up in shock, Bardock simply believed the visions to be nothing more than a dream, and quickly set off for Planet Meat to join his comrades in the invasion, but not before seeing his infant son for the first time. Bardock initially believes his son sees the visions of the future as well, but after reading his power level, comments that he has only an average power level, and was apparently not special at all. He bids farewell to his son and heads off for Meat.
Upon arrival to Meat, Bardock finds himself surrounded by thousands of Meatian corpses, thus believing the battle to already have been over. After reading four power levels on his scouter, Bardock sets off to find his crew, only to find them all dead, with the exception of his best friend, Tora. After Tora tells Bardock of the ambush and why Frieza had them killed, Dodoria's Elite return to the battlefield, aiming to kill Bardock as well. Tora dies in Bardock's arms, and Bardock uses Tora's handkerchief as a symbol of his rebellion. In a show of great skill and power, Bardock fights and kills all four of Frieza's elite warriors with relative ease, only to be ambushed by Dodoria himself, and is badly injured by a powerful mouth blast. Dodoria leaves Meat to report back to Freeza, unaware that Bardock was not killed by his blast. Bardock somehow finds the strength to pull himself up and into his space pod, and plots a course back to Planet Vegeta, in hopes of warning his race of their impending doom.
King Vegeta's attack
Meanwhile, King Vegeta, supreme ruler of the Saiyan race, had been plotting to save his young son from Freeza's grasp and to attempt to defeat Frieza and reclaim his rightful throne over his people. King Vegeta gathers his most powerful Saiyan elites and launches an attack on Freeza. Vegeta and his elites arrive on Frieza's spaceship and after killing numerous guards, successfully push their way into Frieza's chamber. However, upon arrival, King Vegeta's men are so stricken with fear, they cower behind their leader.
King Vegeta, alone, launches his attack on Freeza. Freeza effortlessly dodges a swift punch from the Saiyan king, and with an amazing display of power, kills the king with a single punch to the jaw as Zarbon and Dodoria bear witness. Freeza then also slaughters Vegeta's elites, and finally informs Zarbon and Dodoria that it is time to extinguish the Saiyan race with one final attack.
Freeza's "Final Solution"
After nearly being killed on Planet Meat, Bardock lands on Planet Vegeta in hopes of successfully warning his people of their impending deaths. Try as he might, Bardock is unable to be taken seriously, and is just mocked and laughed at by those he tries to inform. After realizing his efforts are futile, Bardock sees the tyrant's ship looming over his planet, and decides to face Freeza and his entire army... alone.
As Frieza's ship looms over Planet Vegeta, the final hour arrives. Bardock, who realizes his visions of the future are in fact a complete reality, flies up toward Frieza's ship, in the hopes that he may be able to thwart the tyrant's attack. After witnessing Bardock's approach, Frieza orders his army to be released and to engage the lone Saiyan warrior. After killing numerous soldiers, Bardock eventually makes it to Frieza's ship, and calls the tyrant out for one final confrontation. Freeza then appears from his ship, comfortably sitting on his hoverchair.
After informing Freeza of his people's separation from Freeza's empire, Bardock launches a powerful energy ball at the tyrant. However, Freeza, with the lift of a finger, creates a massive sun-like energy ball, which he launches at Bardock and the planet below. After having a final vision of his son's confrontation with Frieza in the distant future, Bardock realizes it will be his son that will be the one to defeat Frieza, and with this, Bardock finds himself at peace before finally being obliterated by Frieza's bomb, along with the thousands of Frieza's own soldiers close by. The energy ball then proceeds to slam into Planet Vegeta, and after burying itself into the planet's core, Planet Vegeta blows up, killing nearly the entire Saiyan race in the process. Observing the "beautiful fireworks", Frieza laughs and congratulates himself on his new found "accomplishment" before leaving in his ship to continue business as usual. In a single day, the mighty Saiyan race was drawn near complete extinction - and the organization which betrayed them to this fate, did not even flinch.
Miles away in space, a space pod containing a baby by the name of "Kakarot" lands on Earth. He is found by an old man named Gohan, who takes the child in and renames him, "Goku". This young boy would grow up into the powerful warrior who would one day prove the Super Saiyan legend true and reclaim his race's honor by defeating Frieza over two decades later. Prince Vegeta, the young son of the now late King Vegeta, and his aid, the Saiyan army general Nappa, both also survive, as they are on an assignment when the planet was destroyed. Upon being informed by a soldier that his planet collided with a large meteor and was destroyed, Vegeta's simple response is nothing but an "oh... really?", but this event would come back to haunt him many years later. Raditz, Goku's older brother and the first son of Bardock also survives, but it is never explained how. It is simply assumed he was on another planet or on an assignment during the event.
Other Saiyans, ones who all appear in Dragon Ball Z films, are also survivors. The first revealed is Turles, a Saiyan who escaped and left Planet Vegeta many years before it's destruction. He went on to become a bounty hunter, but when he journeys to Earth, he and his team are defeated and killed by Goku. Paragus and his son Broly also survive thanks to Broly using his already incredible powers to produce a barrier for them. Broly is revealed to be the Legendary Super Saiyan, and when Vegeta and the others are invited by Paragus to visit New Planet Vegeta, they learn of Broly's origins and power. In the ensuing battle, Broly kills his father ( without remorse) and nearly the Z Fighters, but Goku eventually defeats Broly. However he survives and lands on Earth, where he remains frozen for seven years only to be finally vanquished by Goku's sons Gohan and Goten. He is also later cloned, but defeated by Goten and Vegeta's son, Trunks. Just recently in the new special Yo! Son Goku and His Friends Return!!, Vegeta is revealed to have a long lost brother named Tarble who comes to Earth seeking help. Despite his place in the royal bloodline, Tarble's power level was considered weak and thus he was sent on assignment elsewhere long before the planet's destruction.