Nepal is a mountainous country with about 77% of its total area consisting of mountains, hills, elevated plains (locally known as tars) and river valleys. In general, the topographic altitude increases from south towards north. If the highest peak is Mount Everest (8849m) on the north, the lowest point from sea level is the southern part of Saptari District (61m) in the tarai plain on the south. Topographically, the country is popularly divided into the following three units: -

(a) Himalayan Region: It occurs in the northern part of Nepal and contains various Himalayan Ranges with lofty peaks like Mt Everest (8848m), Kanchanjunga (8598m), Dhaulagari (8137m), Annapurna (8091m) and so on. There are some 200 peaks of over 6000m and 13 peaks of over 8000m. Including the sub-Himalayan areas of over 3000m. this region represents approx 27% of the total area of Nepal.

(b) Hilly Region: The region is very extensive and covers about 50% of the total area of Nepal. Its elevation ranges from 600m to 3000m. Its topography consists of Mahabharat Ranges, Churia Hills, and elevated flattish land and river valleys.  There are some isolated broad valleys lying in between the Mahabharat and Churia Ranges. These are known as Duns or Inner Tarai.

(c) Tarai Region: It is the plain region whose elevation runs up to 300m from sea level. It occurs in the southern part of Nepal and covers some 23% of the total area of Nepal.  It has been formed out of alluvium brought and deposited by the rivers flowing from the northern mountain region; and as such it is of tremendous significance from the agricultural point of view.