For example:
1st Post: 1000 BC: Several former nomadic tribes with a total population of 200,000 settle down and form a loose confederation known as Examplenation.
2nd Post: 100 ENF: A new calendar is invented, starting from the founding of the nation.
3rd post: 200 ENF: The most powerful tribal leader defeats the others and declares that he is now king of Examplenation.
4th post: 210 ENF: The other tribes rebel and defeat him. Examplenation once again returns to being a loose oligarchic confederation.
5th post: 400 ENF: The nation has prospered, total population is now 400,000.
6th post: 500 ENF: The nation is invaded by the nearby Someplace Empire, which makes the area a province.
7th post: 900 ENF: The Someplace Empire collapses after being attacked by barbarians. Examplenation becomes an independent kingdom with a population of 700,000.
And so on...
I'll start:
1000 AD: The United Duchy of Violetia-Maxville is formed, led by Max I of the House of Barry. (Feel free to rename a country if it seems realistic, for example if there are sudden culture changes or if the country expands significantly.)