External relations of Guernsey both islands retain their independence with regards to domestic affairs but internationally, the islands would be regarded as one state. A Guernsey-Jersey double taxation agreement was first signed in 1956. In 1998 Guernsey and Jersey electricity companies formed the Channel Islands Electricity Grid to operate and manage the submarine cables between Europe and the Channel Islands. Guernsey has formed part of the British–Irish Council since it was formed in 1999, as does Jersey. Meetings take place twice a year, in 2004, 2010 and 2014 the meetings have taken place in Guernsey. Its stated aim is to "promote the harmonious and
Maritime history of the Channel Islands at La Hougue Bie, Jersey give evidence of either populations living on or visiting the islands. Guernsey and Alderney were separated from mainland Europe around 7,000 BC with Jersey some time after, but even at 4,000 BC the islands were close to the mainland coast for basic boats to move between islands. Archaeological evidence of trade from the Iron Age period is in evidence in the Islands, with goods manufactured on the western coast such as armlets, Breton pottery and amphorae from the Mediterranean indicating trade along the Atlantic coast from Iberia to Ireland. Armorica was the nearest trade zone.