In 973, a single currency was introduced into England in order to bring about political unification, but by concentrating bullion production at many coastal mints, the new rulers of England created an obvious target which attracted a new wave of Viking invasions, which came close to breaking up the kingdom of the English. From 980 onwards, the "Anglo -Saxon Chronicle" records renewed raiding against England. At first, the raids were probing ventures by small numbers of ships' crews, but soon grew in size and effect, until the only way of dealing with the Vikings appeared to be to pay protection money to buy them off: "And in that year it was determined that tribute should first be paid to the Danish men because of the great terror they were causing along the coast. The first payment was 10,000 pounds."