After the ascension of Kronos, the Eternals discovered that Kronos' experiment had increased their powers. With their new abilities, the Eternals then discovered they could join their will and intelligence into one powerful entity which they called the Uni-Mind.
Despite being more unified than ever before, the Eternals still disagreed on the core goals of their society. The majority of the Eternals (about 70%), led by one of Kronos' sons, Zuras, believed that they shouldn't tinker with their cosmic potential and no new Eternals should be created. Another son of Kronos, A'Lars, and a small fraction of their numbers believed they should keep expanding The Machine (the artificial intelligence that served the Eternals) and create new Eternals, via biological and technological methods.
Around 200,000 years ago, the Eternals went to war once more, with A'Lars being pressured to unlock the secrets of reproduction so more soldiers would join the war effort. One day, Sprite, a supporter of Zuras, sneaked into the Llarsite headquarters to deliver a message that A'Lars' mother, Daina, had a proposal to end the war. In the meeting with Zuras and Daina, an agreement was reached: the majority of Eternals would have their minds wiped and one solitary Llarsite would be allowed to found a colony as an experiment. A'Lars was chosen and adopted the name "Mentor" before settling on the lost colony of Titan.
There, he located Sui-San, the sole survivor of the exiled followers of Uranos, and together they used their genetic material to found a new species of Eternal-derived beings, the Titans. They developed Titan into a wonder of science, building the super-computer ISAAC to help them run the environment. As they flourished, some Eternals of Earth started believing that the Zurasian faction had been overly conservative. Little did they know that Sui-San had just given birth to Thanos, who would one day become one of the Universe's greatest menaces.