The Danegeld was an English tribute raised to pay off Viking raiders (usually led by the Danish king) to save the land from being ravaged by the raiders.
Danegeld was continued later under the name tallage.The term has come to be used as a warning and a criticism of paying any coercive payment whether in money or kind (see also appeasement, the policy toward Nazi Germany prior to World War II).

Danegeld - A short history of Danegeld.
Danegeld - Kipling's poem on the tax.