Short note: I usually take the Manga as canon, but of course I´ve seen the anime, so I´m not free of influence. BUT I don´t quite recall all the filler episodes, if there is a contradiction to those. And I really dislike the Saiyan history lesson in GT. I don´t mind others using it in their personal canons, I just don´t want to. After I´ve read a lot of FFs, I missed it that no one ever thought of the Saiyans as a technologically advanced society, so here you go!
As far as I know it was never established when Freeza arrived in the galaxy. I assume at least a hundred Earth years before planet Vegeta was destroyed. Now, before Freeza arrived, the Saiyans already developed space travel and where active throughout parts of the galaxy. I don´t think they purged planets before, but besides making friends they sure got into fights and wars as well. And if it was just cause of their naturally aggressive behaviour. Still, all in all I think they reached a point where they had a more or less stable society and foreign policy. At some point in their history, the Saiyans managed to unite their whole planet under the rule of one leader, which is, together with the advanced technology, the step towards a regulated society. To make sure the growth of the population takes place as wanted and with the optimal results, the first experiments were started to simply make it completely independent of the involved people, meaning babies didn´t have to grow in the womb anymore. [Edit: This was the one thing that made me really happy when I saw DB Minus:D] Since everyone is created equal everyone should get the same opportunity to make the best out of their lives and not be distracted by baby making and baby delivering. Those experiments though didn´t work. The babies were mostly infertile and had bad health, so this course would only lead to slow extinction. Second stage of the course was to deliver babies the natural way again, but this time they were raised by the state after birth, not by their parents. This was also not working as planned, since the lack of a person the baby could relate to after birth led to unsocial and highly aggressive children. What was gained though was the insight that the parents of every child are chosen by the government. The solution was simple: One of the parents had to take care of the child for one Earth year after the delivery, to give the child someone to relate to and have a stable relationship to, before it got handed over to the state for the rest of their childhood and for their education.
The Saiyans are very much like the Humans, so probably their social behaviour was similar. Such a change in internal policies lead of course to an outcry, and part of the population decided to leave the planet and founded colonies on other planets, where they still can live in families like it used to be. Since the Saiyans were very good fighters, some races sure didn´t mind them on their planets for protection.
And now Freeza arrives the scene.