When was Japan made?

The Japanese archipelago began forming some 150 million years ago when four tectonic plates collided: the Pacific Plate, the Eurasian Plate, the North American Plate, and the Philippine Sea Plate. Over the next 100 million years, the resulting landmasses collided and were pulled undersea, forming the long, mountainous islands that would become Japan. At approximately 100,000 years ago, modern humans are known to have arrived from the Asian continent. In the 7th century, Japan began its process of centralization, unifying under a single emperor.