Shield Islands

The Shield Islands are a region in Game of Thrones. They are an archipelago of four islands off the west coast of Westeros. They are in the Reach, the region under the control of House Tyrell of Highgarden. They lie west of the estuary of the Mander river.

In the books
In the Song of Ice and Fire novels the Shield Islands are Greenshield, ruled by House Chester; Greyshield, ruled by House Grimm; Oakenshield, ruled by House Hewett; and Southshield, ruled by House Serry. The Shield Islands are located to the west of Highgarden and serves as a shield to the Mander river from the Iron Islands. When any sign of longships is spotted, the elders in the watch towers will light the beacon fires, which in turn will cause other watch towers to light their own beacons and spread the warning to various villages and towns and castles further inland so that they will not be caught unaware by any attack. They were armed two thousand years before the events of the series by the Gardener King of the time to protect the Reach from the Ironborn.