The history of Bangkok dates at least back to the early 15th century, when it was a village on the west bank of the Chao Phraya River, under the rule of Ayutthaya.[6] Because of its strategic location near the mouth of the river, the town gradually increased in importance. Bangkok initially served as a customs outpost with forts on both sides of the river, and became the site of a siege in 1688 in which the French were expelled from Siam. After the fall of Ayutthaya to the Burmese Empire in 1767, the newly declared King Taksin established his capital at the town, which became the base of the Thonburi Kingdom. In 1782, King Phutthayotfa Chulalok (Rama I) succeeded Taksin, moved the capital to the eastern bank's Rattanakosin Island, thus founding the Rattanakosin Kingdom. The City Pillar was erected on 21 April, which is regarded as the date of foundation of the present city.[7]
Administration of the city was first formalized by King Chulalongkorn in 1906, with the establishment of Monthon Krung Thep Phra Maha Nakhon (มณฑลกรุงเทพพระมหานคร) as a national subdivision. In 1915 the monthon was split into several provinces, the administrative boundaries of which have since further changed. The city in its current form was created in 1972 with the formation of the Bangkok Metropolitan Administration (BMA), following the merger of Phra Nakhon Province on the eastern bank of the Chao Phraya and Thonburi Province on the west during the previous year.[7]