This is highly debatable I suppose but here's a stab.
1. Egypt 3,150 – 3,500 BC King Menes started this country and also started a reign of pharaohs that ruled the country for over three thousand years. The great Pyramids and the Sphinx remain as testament to this country’s ancient history.
2. India 3,000 BC This country was established by a civilization that started in the Indus valley and has since expanded to be today, the seventh biggest by area and the second biggest by population. In its history, India has given the world calculus and other mathematical formulae.
3. Ethiopia 2,500 – 3,000 BC This country is famous for its wilderness but evidence shows from ancient Egyptian texts, that it was one of its biggest trading partners and actually names the country.
4. China 2,100 – 1,600 BC It is believed that the Xia Dynasty was the first in China as there is no evidence of an earlier one. Some of this country’s history can be seen by a visit to The Great Wall of China or The Forbidden City in Beijing.
5. Iran 625 – 559 BC This country that would later become the birth place of the Persian Empire was started by the unification of the local tribes by Medes. Some historical sites are Qom and Persepolis.
6. San Marino 301 AD This city state may be one of the smallest countries in the world but that does not mean that it is not also one of the oldest. It was established by St Marinus who settled there to avoid persecution. Some of itshistory can be witnessed by looking at the old Walls of San Marino.
7. France 486 AD There are many historical sites in this country which has had such an influence on the rest of Europe. It was first established by a unification made by Clovis the first king of France.
8. Bulgaria 632 AD The first Bulgarian Empire was established with Pliska as its capital by Asparukh. Some of its historical sites include the Rila monastery and the Kazanuk Tomb. It has more recently been linked with the invention of the first electrical computer.
9. Japan 660 AD The Japanese nation is said to have been started by its first Emperor, Jimmu. The country is rich in history and perhaps the best place to witness some of that history is at Himeji Castle.
10. Turkey 900 AD This country was established on the sight of the Trojan War by the Seljuk dynasty of Turks as they migrated and later became the birth place of the Ottoman Empire.
(Greece is not here because it was split between Macedonia and Greek city states. Hungary adn Armenia are sometimes listed.)