One of the most enduring villains in the entire Dragon Ball franchise is Frieza and, by extension, his equally evil father King Cold, with the two tyrants lording over a massive collection of brutally conquered planets across the cosmos. Running relatively unopposed until his invasion of Namek in Dragon Ball Z, -- which resulted in a longstanding feud against Goku and the Z Fighters that stretches all the way through to Dragon Ball Super -- Frieza has conquered death on more than one occasion to continue his vendetta against the Saiyans. However, a villainous legacy as large as Frieza and King Cold's begs the question: how were they able to build their empire in the first place?
Frieza and King Cold are revealed to be in the business of buying and selling planets from native civilizations to the highest bidder across the universe. It was for this purpose that King Cold conquered Planet Vegeta and the Saiyans, with the warrior race becoming integral to their interplanetary trade business model, providing the muscle needed to steal new planets. However, while integral, Freiza's eventual destruction of Planet Vegeta proved that the Saiyans weren't entirely necessary, a fact made even more apparent after the reveal that King Cold's empire was in full swing without them centuries earlier.
When Frieza destroyed Planet Vegeta with a single, epic energy blast, Goku's father Bardock was sucked into a singularity caused by the planetary explosion and flung centuries into the past. Bardock finds himself on the prehistoric world of Planet Plant, Planet Vegeta's original name until it was eventually conquered by the Saiyans. In this distant past, the planet is threatened by King Cold's ancestor Chilled, who distinctly resembles Frieza. As Bardock confronts Chilled, he surprisingly achieves the Super Saiyan transformation and mortally wounds Chilled when the villain attempts to destroy Planet Plant.
This manga side story, Dragon Ball: Episode of Bardock, was written and illustrated by Naho Oishi before eventually being adapted into a film of the same name in 2011. Franchise creator Akira Toriyama contributed directly to the project by providing the design for Chilled, further lending its insight into the origins of Frieza and King Cold's race.
Chilled's activities, and the suggestion that he had a wider family conquering worlds elsewhere, means that King Cold's line had steadily been building their empire for some time, though Chilled's defeat at the hands of Bardock presumably led them to avoid dealing with Planet Plant/Vegeta again for centuries due to the reputed legend of the Super Saiyans.
Frieza was last seen at the end of Broly, returning to rebuild his empire by conquering new worlds, all while vowing revenge on Goku and Vegeta for his latest humiliation at their hands. And with an empire that has been steadily growing for centuries, the Frieza Force and its lucrative interplanetary trade business has been thriving for some time. Frieza has leapt back into the family business like no time has passed at all since his death and, as he licks his wounds and rebuilds his empire, it's only a matter of time before he sets his sights on Earth once again.