Humans first set foot on Thessia Major 23 standard millennia ago, when the Trestunarion, the single longest-lived institution with a contiguous history, was already 155 millennia old. It is estimated that the Mandate of Emmet was at least a century old then, and due to temporal incongruity, it is still unclear how much time passed between the fated date of January 1, 5000 A.D. and his epoch.

Altogether, then, the human clade has been away from Mother Terra's soils for probably not less than 180 thousand years. For such a vast swath of time—far longer than the histories of most other space-faring civilizations—it is singularly remarkable that this ancient time still holds so much meaning in the modern day, both among posthuman societies and those that they have impacted.

This section of the Memory's site will not attempt to catalogue everything there is to say about ancient Earth, nor even the ways in which it has impacted Thet. But it will attempt to shed light on why Earth has had such a powerful impact on our contemporaries and some of the crucial moments in history where knowledge of Terran culture changed the course of events.