As is evident from the name, the district of East Garo Hils is a hilly terrain. The hills are highly dissected and one major formation is the Arbella Range, which is cuts through the south-central part of the district. The range consists of peaks with an average height of 700 metres above sea level. Another important physiographic feature is the Simsang Valley which runs through the southern part of the district. The River Simsang is the longest river in Garo Hills, which originates in West Garo Hills and flows through East Garo Hills and thence to South Garo Hills. The topography of the rest of the district is of undulating low hills, with altitude ranging from 150 to 600 netres above sea level. Besides the Simsang (Someshwari), the district is also drained by the rivers Manda (Dudhnoi) & Damring (Krishnoi), which have their sources within the district. Other than the Simsang which drains southeastwards, the others all runs north or northwest towards the Brahmaputra.