Human habitation in the Japanese archipelago can be traced back to prehistoric times. The Jōmon period, named after its "cord-marked" pottery, was followed by the Yayoi in the first millennium BC, when new technologies were introduced from continental Asia. During this period, in the first century AD, the first known written reference to Japan was recorded in the Chinese Book of Han. Between the third century and the eighth century, Japan's many kingdoms and tribes gradually came to be unified under a centralized government, nominally controlled by the Emperor. The imperial dynasty established at this time continues to reign over Japan to this day. In 794, a new imperial capital was established at Heian-kyō (modern Kyoto), marking the beginning of the Heian period, which lasted until 1185.