The Norman de Long and le Lung arrived in the 11th century with the Anglo-Norman conquest in 1066 AD and established in numerous locations.
A number of Irish Gaelic septs of O'Longain and O'Longaig contributed to the origin of the name.
The name is found in its greatest numbers in Munster, County Cork being most favored.
The line of direct descent from the last elected chieftain to the present day is unbroken — the official title is styled "O'Long of Carrenelongy".
Around the Swedish emigration to the United States the name was anglicised from Långbäck to Longback, Long and Longbrook.