Henan's terrain slopes from west to east. It is bisected from north to south by the Beijing- Guangzhou Railway, which is flanked on the west by hills and mountains and on the east by a vast plain. On its northwestern border is the Taihang range. The western mountain area includes the eastern extensions of the Qinling range--the Yaoshan, Xionger, Waifang and Funiu mountains. Extending east from the Waifang Mountains is Songshan, one of the country's five sacred mountains, whose main peak towers 1,440 meters above sea level. The low, flat Nanyang Basin in the southwest has always been a natural passage between north and south. On the southern border is the Tongbai range, which stretches east to adjoin the Dabie Mountains. The wide plain east of the Beijing-Guangzhou Railway is part of the North. China Plain and the principal farming area of the province. The Huanghe River, which has burst over its dykes and changed its course many times, has left broken dykes and sand dunes in the north of the plain. Of the province's total area, mountains make up 26 per cent, hills 18 per cent and plains 56 per cent.
The Huanghe and Huaihe rivers are Henan's main waterways. The Huanghe River runs through the northern part of Henan from west to east for 700 kilometers. It is narrow and flows swiftly west of Mengjin, where a key water conservancy project has been built over the Sanmenxia Gorge. East of Mengjin it flows slowly across a vast expanse of flatland, where its silt-choked bed rises higher than its banks. The Huaihe River flows through southern Henan from west to east for 300 kilometers, draining an area 43 per cent of its total catchment area.