Archaeological research indicates that people lived in Japan as early as the Upper Paleolithic period. The first written mention of Japan is in Chinese history texts from the 1st century AD. Influence from other regions, mainly China, followed by periods of isolation, later from Western European influence, has characterised Japan's history. From the 12th century until 1868, Japan was ruled by successive feudal military shoguns in the name of the Emperor. Japan entered into a long period of isolation in the early 17th century, which was only ended in 1853 when a United States fleet pressured Japan to open to the West.