Tumlong is a village in the Indian state of Sikkim in northeastern India.

It is located in the Mangan sub division of North Sikkim district.

In 1861, the capital was moved to Gangtok in order to be closer to the Darjeeling district, which was under the administration of the British Raj.

After repeated raids, the capital was shifted to Tumlong, further inland, in 1793 by Tshudpud Namgyal.

In Tumlong (specifically in Phodong under the same gram panchayat) there is a Primary Health Centre (PHC) with two residential doctors and a staff including nurses.