The Washing was a period of Faelish history marked by the large-scale settlement of Faeland by Celtic peoples, mostly from the Continent. The settlement resulted in the breakdown of large states and a return to tribal chiefdoms before and eventual re-emergence of Faelo-Celtic petty kingdoms, as well as a fusion of local and continental cultures. This period also marks the introduction of horses onto the isles as well as the technology of the chariot.
According to a well-established theory, prior to becoming known to the Faelish world, Gaelic speaking tribes were part of the many confederacies of continental Europe. The Celts who invaded Faeland emerged from obscurity when the westward movement of outlier tribes in the 6th and 5th centuries BCE started the great migration of the would-be Faelish overlords, who settled the lands occupied by Faelish cultures, westward into the country encircled by the mountains and south into the Vincennes Basin; then back southeastward into The Shore.
The political result was an island inhabited by Celto-Faelish tribes woven together by a complex tribe system, which was never altogether unified at any point in time. The fundamental unit of Washing-era society was the clan, which itself consisted of one or more families. Each clan had a council of elders, and initially a chief. The regional ethnic groups or tribes (as the Romans later called them) were organized into larger alliances called Deins (pr. "danes"). These defensive groupings would coalesce into kingdoms and petty states by the middle ages as borders and relations stabilized during the period of Roman contact.