Darjeeling superintendent J. W. Edgar, who surveyed the area for the construction of a road to Tibet in 1874, described Kupup as "a grassy and rather marshy valley".

To the southeast of Kupup, the Bitang Tso is considered the source of the Dichu River, even though other streams flowing down from the Dongkya Range provide a greater volume of water.

Dichu flows southeast until Mount Gipmochi on the western shoulder of the Doklam plateau, where it turns south and enters Bhutan.

The cart road to Jelep La on Sikkim–Tibet border, eventually laid by the British, ran on the watershed between Teesta and Dichu rivers.

[7] A road to the Doka La pass near Mount Gipmochi, 5 km distant, runs from Kupup on the northeast side of the valley.