How Germany ordered workers by treaty from 1955.
West Germany signed recruitment agreements with Italy in 1955, Spain and Greece in 1960, Turkey in 1961, later Morocco, Portugal, Tunisia and Yugoslavia. The idea: temporary work, then return. On 23 November 1973 recruitment was stopped because of the oil crisis. Many stayed and brought their families. The word "guest worker" described what did not happen.
Useful: Temporary arrangements in politics often become permanent reality.
Source: de.wikipedia.org