The refers to a 1,600 km² area of flat land, the largest plain in the Kinki region, including a large part of Osaka Prefecture

Osaka Prefecture

is a prefecture located in the Kansai region on Honshū, the main island of Japan. The capital is the city of Osaka. It is the center of Osaka-Kobe-Kyoto area.- History :...

 and a southeastern portion of Hyōgo Prefecture

Hyogo Prefecture

is a prefecture of Japan located in the Kansai region on Honshū island. The capital is Kobe.The prefecture's name was previously alternately spelled as Hiogo.- History :...

. It is bordered on the north by the Hokusetsu Mount Range, on the east by the Ikoma Mount Range and Kongō Mount Range, on the south by the Izumi Mount Range, and on the west by Osaka Bay

Osaka Bay

Osaka Bay is a bay in western Japan. As an eastern part of the Inland Sea, it is separated from the Pacific Ocean by the Kii Channel and from the neighbor western part of the Inland Sea by the Akashi Strait...

. On occasion, it is called the after the names of former Settsu Province

Settsu Province

was a province of Japan, which today comprises the eastern part of Hyōgo Prefecture and the northern part of Osaka Prefecture. It was also referred to as or .Osaka and Osaka Castle were the main center of the province.-History:...

, Kawachi Province

Kawachi Province

was a province of Japan in the eastern part of modern Osaka Prefecture. It originally held the southwestern area that was split off into Izumi Province...

 and Izumi Province

Izumi Province

was a province of Japan. It is also referred to as . It lay in Kinai, and its area today composes the south-western part of Osaka Prefecture . The Ōshōji in Sakai was the border with Settsu Province, until the beginning of the Meiji period, when the boundary was changed to be at the Yamato River...

.

Geologically, the plain is considered to be an alluvial plain mainly consisting of hills and plateaus created during Pliocene

Pliocene

The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...

 and Pleistocene

Pleistocene

The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....

 and deltas created during Holocene

Holocene

The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...

 by current rivers such as the Yodogawa River and Yamatogawa River. Prominent hills and plateaus include the Senri Hills, Toyonaka Plateau, and Itami Plateau to the north; the Hirakata Hills and Katano Plateau to the northeast; and the Kasen Hills, Shinodayama Plateau, Mikunigaoka Plateau, and Uemachi Plateau

Uemachi Plateau

The Uemachi Plateau is a plateau in Osaka city, Japan, that extends from the Osaka Castle and Tenmabashi area to Tennōji in the south.- History and formation :...

 to the south. Major streams are the Muko River, Ina River

Ina River

The Ina is a river in northwestern Poland, a right tributary of the Oder River.The origins of the river are in Insko Lake , and it flows through a succession of smaller lakes. A confluence of Ina River is localized in Police, Poland town...

, Ibaraki River, and Akuta River located in the northern portion; and the Yodo River and Yamato River in the eastern section; and the Ishizu River, Ōtsu River, and Onosato River in the southwestern part of the plain.