The Attack on Zeshin and Buns' planet is an attack administered by Cui, one of Frieza's elite henchmen. He and a group of eleven other Frieza Force soldiers invaded the planet and killed several of it's people to conquer the planet and make the inhabitants profess Frieza as their new ruler and owner of their planet if they want to be spared though they never had intentions on sparing the inhabitants of the planet in the beginning and continued to murder any inhabitants that were still on the planet. At one point in the conflict, Cui found and scarred Bun in the face. A group of children from the planet, which included Zeshin, Bun himself, and Emi were able to get away by using an invisible spaceship while other children who fled were killed if their spaceships were caught in space.
The invasion possibly started out when Cui and eleven others landed on Zeshin and Bun's planet attacking everyone they see on sight.