The seven Emirates that now form this federation signed the original General Treaty with Britain in 1820, whereby they agreed to fly flags of red and white rather than plain red, and this reason their territory became known as the Trucial Coast, or Trucial Oman.
The states first formed a federation in 1968, with a flag of white with red colored bands at the top and bottom and a green colored 7-pointed star in the center. But when the federation became independent under its new name, the present flag was adopted in the traditional Arab colors.
The red vertical band along the hoist refers to the fact that this is the basic color of the flags of the member-states. The arms are a falcon beating a ship on a red colored disc withing a chain of eight links.
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