It is the Shaanxi region.
The Weihe Plain, also known as the Guanzhong Plain or the Weihe Basin, is a graben-type structural plain. In order to distinguish the Guandong and Guanxi regions, the Guandong region is located in the area east of Jiayuguan, and Guanxi is west of Jiayuguan, so it is called Guanzhong. It is located in the central part of Shaanxi Province, between the Qinling Mountains and the Weibei Beishan Mountains (Laolong Mountain, Saga Mountain, Yaowang Mountain, Yao Mountain, etc.). It starts from Baoji in the west and ends at Tongguan in the east, with an altitude of about 325 to 800 meters and a length of about 300 kilometers from east to west. It covers an area of ??approximately 34,000 square kilometers. Because it is between Hangu Pass and Dashan Pass (some say it is between Hangu Pass, Dashan Pass, Wuguan and Xiaoguan), it was called "Guanzhong" in ancient times. During the Spring and Autumn Period and the Warring States Period, it was the hometown of the Qin State, including the five cities of Xi'an, Baoji, Xianyang, Weinan, Tongchuan and Yangling District. It is 300 kilometers long from east to west, with an average altitude of about 500 meters. It is narrow in the west and wide in the east. It is known as the "Eight Hundred Miles of Qinchuan". Irrigation has been developed here since ancient times and it is rich in wheat, cotton, etc. It is an important commercial grain-producing area in my country. The Weihe Plain is located in the central part of Shaanxi Province. It is the richest place in Shaanxi and the first place in China known as "The Golden City Thousand Miles, the Land of Abundance".