Ortah was a landlocked kingdom of Derlavai, sandwiched between Algarve and Unkerlant. The Ortahoin (singular: Ortaho) were believed to be related to the Ice People, as their languages were very similar.
It maintained an isolationist foreign policy, which was supported by its mountainous and swampy topography. Under King Ahinadab, Ortah remained neutral throughout most of the Derlavaian War. Near the end of the war, Unkerlant, in the final drive to Trapani, invaded Ortah. After the fighting ended, Ortah became an Unkerlanter satellite like Forthweg and Yanina.
Ortah is based primarily on Switzerland, although its invasion by Unkerlant, and subsequent status as an Unkerlanter satellite, breaks that analog.
The Swiss analog is also broken by the detail of Ortah's language being unrelated to any neighboring tongue. This may be based on the phenomenon of the Basques, which Harry Turtledove has referenced on other occasions. The Ortaho language as given in the novels is based on Aramaic, while the related Ice People language is based on Hebrew.