The planet Vegeta is a large planet, mainly uninhabited. In the north, the planet is a complete wasteland, consisting mainly out of hot deserts. The whole south of the planet is covered in lush forests that stretch out over the entire planet. In the absolute south of the planet, there are big mountains on which lay snow. In the absolute north, there is a mountain range that consists out of vulcanos.
The Saiya-Jin chose to build their cities in the deserted wastelands which are far better equipped to handle their training than the lush south would.