On December 1, 1965 the erstwhile North-East Frontier Agency was divided into five districts:
- Kameng district
- Subansiri district
- Siang district
- Lohit district
- Tirap district
On May 13, 1980, Subansiri district was bifurcated into two districts: Lower Subansiri district and Upper Subansiri district. Upper Subansiri district comprised the area occupied by the erstwhile Daporijo sub-division and Lower Subansiri district comprised the rest of the area occupied by the erstwhile Subansiri district.
On June 1, 1980, the erstwhile Lohit district was divided into two districts: Lohit district and Dibang Valley district. On the same day, Siang district was bifurcated into two districts: East Siang district and West Siang district. And Sepla and Bomdila sub-divisions of the Kameng district were transformed into East Kameng district and West Kameng district, respectively.
On October 6, 1984, Tawang district was separated from East Kameng district.
In 1987, the ersthwile Tirap district was divided into two districts: Tirap district and Changlang district.
On September 22, 1992, the erstwhile Lower Subansiri district was again bufurcated into Lower Subansiri district and Papum Pare district.
In 1999, Upper Siang district was split from East Siang district.
In June 2000, Kurung Kumey district was carved out from the erstwhile Lower Subansiri district.
On December 16, 2001, Dibang Valley district was bifurcated into Upper Dibang Valley district and Lower Dibang Valley district.
On February 16, 2004, Anjaw district was carved out from the erstwhile Lohit district.
On March 19, 2012, Longding district was carved out from the erstwhile Tirap district.
On November 17, 2014, Namsai district was carved out from the erstwhile Lohit district.
On February 8, 2015, Kra Daadi district was carved out from the erstwhile Kurung Kumey district.
On November 27, 2015, a new Siang district was carved out from parts of East Siang and West Siang districts.
The districts of Arunachal Pradesh state are administrative geographical units, each headed by a deputy commissioner, an officer belonging to the Indian Administrative Service and a superintendent of police, an officer belonging to the Indian Police Service.
Kameng Division (Bomdila): Tawang, West Kameng, East Kameng
Subansiri Division (Ziro): Papum Pare, Kurung Kumey, Kra Daadi, Lower Subansiri, Upper Subansiri
Siang Division (Pasighat): West Siang, West Siang, Central Siang, Upper Siang
Lohit-Dibang Division (Tezu): Upper Dibang Valley, Lower Dibang Valley, Anjaw, Lohit, Namsai
Tirap Division (Khonsa): Changlang, Tirap, Longding
As of 2016, Arunachal Pradesh comprises 20 districts. Most of them are inhabited by various tribal groups. These are:
Rima district, from Changlang district. Sub-divisions: Diyun, Bordumsa, Kharsang, Jairampur, Nampong, Rima-Putak (Tikhak), Miao, and Vijoynagar
Lower Siang district with headquarter in Likabali, from West Siang district and East Siang district
Itanagar district, from Papum Pare district. Sub-divisions: Tarasso, Balijan, Sangdupota, Banderdava, Itanagar, and Naharlagun.
Sagalee district, from Papum Pare district. Sub-divisions: Sagalee, Leporiang, Parang, and Mengio.
North Subansiri district, from Kurung Kumey (Sub-divisions of Sarli, Damin), Kra Daadi (Sub-division of Pipsorang/Longding Koling) and Upper Subansiri (Sub-divisions of Taksing, Limeking, Nacho, Siyum) districts.
Leparada district with headquarter in Basar
Hayuliang district, from Anjaw district (Sub-divisions of Hayuliang, Metengliang, Chaglagam, Goiliang) and northeastern parts of Tezu circle in Lohit district.
