It is difficult to tell when the first people settled in Japan, but based on archaeological evidence, it appears that the first people to settle in Japan arrived in the area approximately 30,000 years ago. This information has been gathered using carbon dating, focusing on certain pieces of pottery that have survived to this day. Around 1,000 BC, the Yayoi people started to arrive in the area from Kyushu, and they intermingled with a lot of other people who lived in the area at the time. Even though it is difficult to trace the history of a country back this far, it appears that people have lived on the islands of Japan for tens of thousands of years.
It is said that the very first ruler of Imperial Japan was Emperor Jimmu. He is set to be the grandson of a famous God in Japanese history, and he ruled central Japan starting in 660 BC. The first few emperors of Japan are largely known from legends that have been written and passed down from generation to generation. It is very difficult to accurately tell what is historical and what is legend.
Then, for more than a thousand years, Japan was ruled by the shogunate. The ruler of Japan was passed down in a line, aside from a few periods of brief Civil War. Both classical and feudal Japan were ruled in this manner.
Starting with the Meiji Period in 1868, Japan was ruled by Emperor Meiji. Prior to that time, Japan was following a very isolationist governing style. Japan was not open to other countries, but it was eventually forced to open by the Western powers. At this time, Japan knew that it would have to open itself up to compete on the global stage. This led to the growth of the Empire of Japan, and it modernized quickly. The goal was to create an Asia-Pacific sphere of influence, with Japan at the helm. Even though Japan was claiming that Asia should be left to Asians, it wanted to rule all of the Eastern portions of the world. As a result, Japan went to work conquering China, Korea, and numerous other smaller countries across the Pacific Ocean.
Eventually, the Empire of Japan will be defeated by the United States at the end of WWII in 1945. This brought the Empire of Japan to an end and led to the growth of a modern, democratic Japan. The United States occupied Japan for a few years following the end of World War Two, but eventually passed control of Japan back to a new Japanese government. Therefore, the modern history of democratic Japan dates back to the end of World War Two. On the other hand, people have lived on the islands of Japan for tens of thousands of years dating back to prehistory.
The country of Japan is 1624 years old, founded in the year 400.