evidence: India's Sikkim state lies to the west of the Dongkya range, the western shoulder of the Doklam plateau and the 'southwest spur' issuing from Mount Gipmochi. This spur is cut by the Dichu river (also called Jaldhaka) which originates below the Jelep La pass and enters Bhutan. The 'southeast spur', called Zompelri ridge, separates Bhutan's Haa District (to the north) from the Samtse (to the south). [...] According to Sikkimese tradition, when the Kingdom of Sikkim was founded in 1642, it included all the areas surrounding the Doklam plateau: the Chumbi Valley to the north, the Haa Valley to the east as well as the Darjeeling and Kalimpong areas to the southwest. During the 18th century, Sikkim faced repeated raids from Bhutan and these areas often changed hands. After a Bhutanese attack in 1780, a settlement was reached, which resulted in the transfer of the Haa valley and the Kalimpong area to Bhutan. The Doklam plateau sandwiched between these regions is likely to have been part of these territories. The Chumbi Valley was still said to have been under the control of Sikkim at this point.[36][37] [...] Depictions of historical Chinese maps by the People's Republic of China show Sikkim and Bhutan as part of Tibet or China for a period of 1800 years, starting from the second century B.C., noted as dubious claims by scholars.[h] From 1958, Chinese maps started showing large parts of Bhutanese territory as part of China.[62]