The annual Inthakin Festival (starts on the 12th day of the waning moon of the 6th lunar month and lasts for 8 days) is a custom held to propitiate Chiang Mai's guardian spirit. King Mengrai founded the city of Chiang Mai (meaning 'new city') in 1296, and it succeeded Chiang Rai as capital of the Lanna kingdom. The ruler was known as the Chao. The city was surrounded by a moat and a defensive wall, since nearby Burma was a constant threat. Chiang Mai formally became part of Siam in 1774 by an agreement with Chao Kavila, after the Thai King Taksin helped drive out the Burmese. Chiang Mai then slowly grew in cultural, trading and economic importance to its current status as the unofficial capital of northern Thailand, second in importance only to Bangkok.