Thailand (Kingdom of Thailand) has a tricolor flag with five stripes instead of just three. The colors of the flag are in this order: red – white – blue – white – red. The blue band at the middle is twice the width of any of the four other stripes. The flag’s Thai name is Thong Trairong simply meaning tricolor flag.
This flag was adopted as the national flag of the Kingdom of Thailand in September 28, 1917 as per royal decree on national flag issued that year. Before that year, however, Thailand’s flag underwent several changes before finally being the tricolor flag it is today.
The flag used under King Narai, who ruled Thailand (then called Siam) from 1656 to 1688, was a plain red flag and was probably that first flag that Thailand used. A red flag with a white chackra on the center, as according to the decree by Rama I (King Buddha Yodfa Chulaloke), has been used since 1790 to 1820. Another variant of the flag of Thailand has a white elephant inside the chakra.
But the first official flag of Thailand was the one created by Rama IV (King Mongkut). The flag showed a white elephant with a red background because the plan red flag was deemed not distinct enough for used in international relations. In 1917, the flag used had the current design but the middle stripe was the same with the outer stripe in width and color (red). It was changed and made symmetrical by Rama VI (King Vajiravudh).
The middle color was changed to dark blue in 1917. It was similar in tone with indigo, which was then considered lucky color for Saturday, the day Rama VI was born. According to some sources, though, it was to show solidarity with the Allies of the First World War that also bear blue-white-red flags.