A new walled-city with a surrounding moat, designated as Nakhon Ratchasima, was built in the 17th century by order of the King Narai, as the easternmost "command post", guarding the kingdom's border. It continued this duty during the Bangkok Period, although it was briefly seized during Chao Anuwong of Vientiane's 1826 revolt against King Rama III of Siam.
Nakhon Ratchasima has long been the most important political and economic centre in the northeastern region. In the late-19th century, the railroad reached Khorat and it became the junction of two main rail lines in the northeastern, Isan, region. In 1933 it was the stronghold of the royalist troops in the Boworadej Revolt, as they fought against the new ostensibly democratic government in Bangkok. In the 1950s, the Korat Royal Thai Air Force Base was built in Nakhon Ratchasima; from 1961 until 26 February 1976, this facility was also used as a base by the United States Air Force.