This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Islam reaches Western Europe in its modern, demographically significant form through the labor migrations that followed the Second World War, as postwar labor shortages across the continent drew large Muslim immigrant populations into Western European countries between 1945 and 1980. Germany's guest worker program is the most visible case, recruiting foreign labor from 1955 to 1973 and bringing roughly 867,000 Turkish workers into the country by 1973.
Each receiving country's Muslim population arrived along its own particular route rather than a single shared migration. Germany's came chiefly through its formal guest worker recruitment from Turkey. France's Muslim population grew mainly through North African immigration, following the country's own colonial ties to North Africa. Britain's followed South Asian immigration, carried by its own colonial and labor history with the Indian subcontinent, so that three of Western Europe's largest Muslim communities each trace back to a distinct national history rather than one common cause.
What this changed for Islam's spread was the arrival, within a single postwar generation, of a Muslim presence across Western Europe substantial enough to become a permanent feature of the continent's religious landscape, reaching countries with no prior history of significant Muslim settlement through labor rather than conquest, trade or missionary activity.