A paleocivilization is one which existed long before the rise of the modern Stellar Compact or even any of its constituent sapient species. Single-planet civilizations, which collapsed into extinction before achieving space colonization, are known to have existed on multiple Starweb worlds, such as Jefferson and Sheol. Ruins of interstellar empires, some of which embody technologies far in advance of the best known science, have also been found.
- Space-Weavers: Unknown time period, megayears to gigayears before present. Responsible for numerous spacetime metric artifacts, anomalies, and structures in Starweb space. Note that some xenologists consider the Space-Weavers and the Geometricians to have been the same civilization as no material Space-Weaver artifacts have ever been identified.
- Geometricians: c. 315 million years ago, spacefaring, notable for simplistic geometric shapes in their ruins.
- Ancient Jeffersonians: c. 52 million years ago, early-digital/fossil fuel age planetary civilization.
- Enclaver Empires: ~100,000 - 10,000 years ago, series of interstellar civilizations leaving behind a vast volume of space still full of functioning superscientific technology.