Chiba Prefecture (, Chiba-ken) is a prefecture of Japan located in the Kant region and the Greater Tokyo Area. Its capital is Chiba City. Chiba Prefecture was established on June 15, 1873 with the merger of Kisarazu Prefecture and Inba Prefecture. Historically, the prefecture constituted three provinces of Awa, Kazusa, and Shimsa. The prefecture's name means "a thousand leaves". Chiba borders Ibaraki Prefecture to the north at the Tone River, Tokyo and Saitama Prefecture to the west at the Edo River, the Pacific Ocean to the east and Tokyo Bay around its southern boundary. Most of Chiba lies on the hilly Boso Peninsula, a rice farming region: the east coast, known as the Ninety-Nine League Plain, is an especially productive area. The most populous zone, in the northwest of the prefecture, is part of the Kant region that extends into the urban agglomeration of Tokyo and Saitama. The Kuroshio Current flows near Chiba, which keeps it relatively warm in winter and cooler in summer than neighbouring Tokyo.