Northern part of modern Henan province with the southern boundary delineated by the Sanmenxia, Luoyang, Zhengzhou, and Kaifeng prefectures. Includes the historic capitals Anyang, Zhengzhou and Luoyang and the archaeologically significant Yi-Luo basin. Area = Sanmenxia (9937), Luoyang (15229), Zhengzhou (7507), Kaifeng (6247), Angyang (7355), Hebi (2182), Jiaozuo (4001), Puyang (1617), Xinxiang (8629). Total: 62,704 KM2. Also includes sub-prefecture level cities Jiyuan (1931), Ruzhou (?) and Gongyi (1041), and the sub-prefecture level counties Lankao (1116), Hua (?), and Changyuan (?).