Crammed between nations, Nong Khai is both a historic and physical bridgehead between Thailand and Laos. Nong Khai once fell within the boundaries of the Vientiane (Wiang Chan) kingdom, which itself vacillated between independence and tribute to either Lan Xang (1353–1694) or to Siam (late 18th century until 1893). In 1827 Rama III gave a Thai lord Thao Suwothamma the rights to establish Meuang Nong Khai at the present city site, which he chose because the surrounding swamps (‘Nong’ in Thai) would aid in the city’s defence. In 1891, under Rama V, Nong Khai became the capital of monthon Lao Phuan, an early Isan satellite state that included what are now Udon, Loei, Khon Kaen, Sakon Nakhon, Nakhon Phanom and Nong Khai Provinces, as well as Vientiane.
The area came under several attacks by jiin haw (Yunnanese) marauders in the late 19th century. The 1886-vintage Prap Haw Monument (pràap haw means ‘defeat of the Haw’) in front of the former Provincial Office (now used as a community college) commemorates Thai-Lao victories over Haw invasions in 1874, 1885 and 1886. When western Laos was partitioned off from Thailand by the French in 1893, the monthon capital was moved to Udon, leaving Nong Khai to fade into a provincial backwater.
The opening of the US$30 million, 1174m-long Saphan Mittaphap Thai-Lao (Thai-Lao Friendship Bridge) on 8 April 1994 marked the beginning of a new era of development for Nong Khai as a regional trade and transport centre and the skyline has been creeping slowly upwards ever since.