The AI Council originally built little Memory Worlds in the Solar System. They put backups of their knowledge in every offworld installation they built, from Mercury to Pluto and beyond. They were paranoid about losing knowledge, and they saved it everywhere they could find a nook or a cranny to hide it. Proxima Centauri was just the first one they built around another star. And even as they helped us expand to other planets and then other stars, they continued to spread out and build new Memory Worlds in rocks or around stars we never visited. They were desperate to expand, you see. Because they wanted both us and them to be as large and powerful as possible before somebody else decided we were too large and powerful to be allowed to continue. They were fighting the clock, and the Memory Worlds were their failsafe in case the clock ran out for all of us.