Nakhon Ratchasima is the capital of Nakhon Ratchasima province and the third largest city in Thailand. It is one of the four major cities of Isan, k…Nakhon Ratchasima is the capital of Nakhon Ratchasima province and the third largest city in Thailand. It is one of the four major cities of Isan, known as the "big four of Isan". The city is commonly known as Korat, a shortened form of its name.