The original national flag of Thailand, in use from perhaps the 17th century, was plain red. When other states in the area displayed similar flags and commerce increased, it became necessary to add a symbol to the design for ready identification. In 1782 a white chakra (wheel), symbol of the ruling Chakri (Chakkri) dynasty, was put on the flag of navy vessels, and in 1855 both navy and privately owned vessels displayed a red flag with a white elephant in the centre. The rare white elephant had long been a symbol of good fortune associated with the nation.