The Siang district was created by bifurcating West Siang and East Siang districts of Arunachal Pradesh consisting of 32-Rumgong-Kaying and 35-Boleng-Pangin Constituencies. The district was inaugurated on 27 November 2015.

The name of the district is derived from the mighty Brahmaputra River, which in Arunachal Pradesh is known as the Siang river.

Geographically, Siang District is located almost in the centre of the Siang belt of Arunachal Pradesh. Pangin is about 80 km from Pasighat, 30 km from Along and 22 km from Boleng

The creation of Siang district was approved by the Government of Arunachal Pradesh on 21 March 2013.

The new district was created to make the administration closer to the public.

Pangin is the headquarter of the district.