The arms are derived from the national flag. Before 1820 the flag of Bahrain was initially plain red, originating from the color of the Kharidjite Muslim sect. In 1820, following the General Maritime Treaty with Britain, a vertical white stripe symbolizing the truce was added at hoist ( but de facto the plain red flag remained in use until 1910). In 1933, to distinguish the flag from other flags in the area (current Ajman and Dubai flags, ancient Abu Dhabi flag) the stripe was serrated [i.e. limited with a zig-zag border], The specific meaning of the serration is unknown.