In the year 1989 the region was shifted from West Siang district to East Siang. After sometime, in 1999, the district was divided and Upper Siang district emerged. The history of the East Siang district is closely associated with the Chutiya Kingdom. Probably, it was under the Chutiya chieftain rule from a long time and then went into the hands of the Birpal's rule in the 12th century.

Geographically, the district has a total area of 3,603 sq. km. and occupies the rank 13th in State and 343th in India on the basis of the size. It lies at 28°08'N latitude, 95°33'E longitude and 155 m altitude. In the year 2021, there was a total 80.81% forest area of total geographical area. The district is bounded by Dhemaji District of Assam on the South, by Upper Siang District on the North, by West Siang District on the West and by Dibang Valley District on the East. The climate of the district remains pleasant almost throughout the year. Most of its rainfall occurs in the monsoon season. The actual rainfall in the district was 3666.3 mm in the year of 2021-22.

Administratively, the district is divided into 15 sub-districts, 2 towns and 151 villages. English is its administrative language. The district came into existence in the year 1989. It has administrative headquarters located at Pasighat Town which is situated at the distance of 265 kms from the State Capital. There are total 5 legislative assembly constituencies in the district namely Panging, Nari-Koyu, Pasighat West, Pasighat East, and Mebo. All of these are the part of Arunachal East Lok Sabha constituency.

Demographically, according to the 2011 census, the district has a total number of 19,095 households with a total population of 99,214 comprising 50,116 are males and 49,098 are females which leads it to rank 6th in the state and 615th in India. The density of population of the district is 25 (persons per sq km.). The sex ratio is pegged at 980 (females per 1000 males) while the child ratio stands at 988 (females per 1000 males). The schedule tribe population of the district is recorded as 69,979 including 34,533 are males, and 35,446 are females. The percentage of Schedule Tribe is 7.35%. As per 2011 census the major religions practiced by the people in the district are Hindu and Christian with 28.07% and 18.40% of the total population. The population growth rate during the period of 2001-2011 was 13.52% including 10.72% were males and 16.53% were females. According to 2011 census the principal language in the district is Adi with 68.73%. In the year 2020 the number of live births in the district was 2,038 out of which 998 were males and 1,040 were females. In the same year the number of deaths in the district was 149 out of which 96 were males and 53 were females.

The district is mainly dependent on the agricultural sector. More than half of the populations are engaged in agriculture in order to earn their livelihood. The chief agricultural products in the district are paddy, maize, millet, mustard, etc. In the year 2021-22 the gross domestic product in the district was Rs. 2,54,382 lakhs at current price and Rs. 1,50,625 lakhs at constant prices in the year 2011-2012. The net domestic product in the district during the period 2021-22 was Rs. 2,34,849 lakh at current price and Rs. 1,35,780 lakh at constant prices in the year 2011-2012. The Per Capita Income or NDDP, At Factor Cost during the period 2021-22 was Rs. 2,14,269 at current price and Rs. 1,23,882 at constant prices in the year 2011-2012.

Education wise, according to the 2011 census, the district has a literacy rate of 72.54% including 78.47% are males and 66.49% are females. The total literate population in the district is 62,576 comprising 34,210 are males and 28,366 are females. The total number of illiterates in the district is 36,638 comprising 15,906 are males and 20,732 are females. Jawaharlal Nehru College, College of Horticulture & Forestry, D Ering Memorial Government Secondary School, Government Higher Secondary School, Doying Gumin College, Jawaharlal Nehru College, Green Valley School and Jawahar Navodaya Vidyalaya are some of the most reputed educational institutions in the district.

Daying Ering, a veteran Indian politician from the NEFA Sangam political party of Arunachal Pradesh was served as the chairman of the Ering Commission. Ninong Ering, another prominent politician from the Indian National Congress was born in the district. He is also the representative of Arunachal East in Lok Sabha. Tapir Gao is a member of the Bharatiya Janata Party who at present serving as the President of the state party. He has also served as the member of 14th Lok Sabha. Tarung Pabin, an illustrious India politician and a member of the Indian National Congress who has won the Legislative Assembly election in the 1990.

The district has several famous historical and religious tourist places which are not only famous within the country but also in the state. These places are Kekar Monying, Daying Ering Wildlife Sanctuary, Pangin and many more. Kekar Monying, an important mountain cliff which is associated with some the battle that the Adi tribes fought against British. A rectangular canal is also present over there. Visitors can reach Daying Ering Wildlife Sanctuary through cruise by the Siang River. It has also a great variety of the migratory birds like instance hornbills, cranes, water fowls, wild ducks, stork, etc. Pangin is situated at the intersection point of the Rivers Siang and Siyom. Visitors can mesmerize scenery of the meeting of green waters of Siang River and the blue waters of Siyom River. Ayeng village, Boleng, Ranaghat at Pasighat, Yambung and Rottung are the other attractive places here to visit. There are several traditional festivals that its natives celebrated very happily are Pime, Etor, Mopin, Ali-Aye Ligang and Unying-Aran. Some of the most significant dance forms in the district are Tapu, Ponung, Gumrak Soman, Yakjong and Delong.