Exactly, countries that over centuries developed into something which is usually a product of specific historic circumstances (like England compared to rest of Europe in EU3 time frame) are one thing.
Unless that specific history is part of actual game history, in this case a country that does not exist in 1399. or has any provincial/country history entries before that (IIRC), i for one think such a country should be given a default form of government of that age and region, which in this case would be a despotic monarchy.
To make it fair, an event chain could also be added, so under certain triggers (something alike real life history) such a country could develop into something else, why not even make specific government for Persia etc. Its a simple way to add lots of flavor to the area and vastly increase the overall game value.