The flag of Bahrain comprises a white band on the hoist side of the flag and a (larger) red band on the fly side of the flag, separated by five triangles that serve as a serrated line.
The original flag of Bahrain was plain red; however, in 1820 Bahrain signed a general maritime treaty with the British Empire which stated that all friendly states in the Gulf region were to add white to their flags so as to not be mistaken for pirates at sea. Bahrain thus added a white stripe to its flag, which was then serrated in twenty eight parts in 1932 before being reduced to eight serrations in 1972. Finally, on 14 February 2002 after Bahrain became a Kingdom, the number of serrations were reduced to five to represent the five pillars of Islam.
The flag's ratio is 3:5.