The process continued, until the dawn of life itself. Hot blasts of dying stars peppered the galaxy, and with each blast the raw materials for world-building — and life itself — became more abundant. But the steady enrichment of metals did not happen uniformly across the disc of the galaxy. In the outlying regions of the galaxy, the cycles of stardeath and starbirth happened on a much slower timescale than in the frantic core zones.
So it was that the first stars to host rocky worlds formed closer to the core, where the metals reached the critical level first It was from the core zones, within a thousand kiloparsecs of the galactic centre itself, that the first starfaring cultures emerged. They looked out into the galactic wilderness, flung envoys across thousands of light-years and imagined themselves alone and unique and somehow privileged. It was a time both of sadness and chilling cosmic potential. They imagined themselves to be lords of creation.
But nothing in the galaxy was that straightforward. Not only were there other cultures emerging at more or less the same galactic epoch, in the same band of habitable stars, but there were also pockets of higher metallicity out in the cold zone: statistical fluctuations which allowed machine-building life to emerge where it ought not to have been possible. There were to be no all-encompassing galactic dominions, for none of these nascent cultures managed to spread across the galaxy before encountering the expansion wave of another rival. It had all happened with blinding speed once the initial conditions were correct.
And yet the initial conditions were themselves changing. The great stellar furnaces had not fallen quiet. Several times a century, heavy stars died as supernovae, outshining all others. Usually they did so behind sooty veils of dust, and their deaths went unrecorded save for a chirp of neutrinos or a seismic tremor of gravitational waves. But the metals that they made still found their way into the interstellar medium. New suns and worlds were still coalescing out of the clouds that had been enriched by each previous stellar cycle. This ceaseless cosmic industry rumbled on, oblivious to the intelligence that it had allowed to flourish.