The Republic of Istanbul was a small city-state in Europe and asia.
Istanbul had long been a part of the Ottoman Empire. In 1821, the Sultan moved the capital away from Istanbul. In 1827, the Greeks besieged Istanbul, but the Ottoman Army would not come. People were really mad at the Ottomans and called for independence. Finally, on October 29, 1828, Istanbul became an independent nation. They were forced to sign treaties with the Ottomans in exchange for recognition. But, when the Ottoman Sultan was deposed and a Turkish republic started, Istanbul had to be wary. Turkey had plans to re-integrate Istanbul into itself. A brief war was fought in 1917, and Istanbul ceased to exist as a country.
In 1921, Istanbul was made an Autonomous Region of Turkey.