The Chronicle of the Seven Ages

The Tidal Age (c. 3.1 million – 61,000 BE) — Life on Ithris began in its tidal seas, where the first creatures signalled to one another in pulses of bioluminescence. The Ithra never stopped speaking in light.

The Age of Lanterns (61,000 – 38,000 BE) — The Ithra cultivated luminous organisms into lanterns and built the first cities on the archipelagos. Writing appeared as sequences of light caught and kept in crystal.

The Resonance (38,000 – 21,000 BE) — The Ithra discovered that a vibrating crystal lattice could hold a pattern indefinitely. They built libraries of resonance beneath the ice of Mereth.

The Quiet Schism (21,000 – 14,500 BE) — A dispute over whether memory should be kept or allowed to fade divided the Ithra. For six thousand turns the two halves of a civilization turned their light away from each other.

The Long Noon (14,500 – 3,200 BE) — The golden age. The Ithra grew orbital gardens in the rings of the giant Sollen, mapped the stars around them, and proved a hard theorem: they were alone.

The Reddening (3,200 – 400 BE) — Vael left its long middle age. Over three thousand turns it reddened and swelled, boiled the seas of Ithris and swallowed Carrow. The Ithra understood they could not leave.

The Great Encoding (400 BE – 0) — On Ennis the Ithra built the Choir: a lattice of transmitters girdling a world. Into it went everything they chose to remember — freely given — cast into the dark as light.