It witnessed a major shift in the political scenario with the National Peoples' Party (NPP), the party from neighbouring Meghalaya, being able to set a footprint in the state's politics by gaining seven MLAs without contesting the 2014 battle of ballots.
The remaining two PPA MLAs on September 20 joined the Congress. After the development, the PPA, the lone regional party of the state was left with no MLA in the 60-member state assembly.
In early January, a similar Doklam-like situation brewed up at Gelling in Upper Siang district of the state with reports that a Chinese road-building team entered the state's territory with bulldozers on December 28, 2017.
According to local villagers, Indian soldiers confronted their Chinese counterparts and seized their road construction machines including two excavators. They also claimed that Chinese soldiers were involved in road construction in that area.
Another major issue which hogged limelight during the year gone by was the Siang river, considered as the lifeline of the state, turning black and muddy at various places and locals suspecting China's role behind the phenomenon.
People in the state, especially those in Pasighat in East Siang district, complained about rise in mud level in the river.
Post the landslide over Yarlung Tsangpo River (Siang in Arunachal Pradesh, Brahmaputra in Assam) in Milin county of Tibet in China, several materials from China were washed by the river floating downstream into India in October.
The Chakma and Hajong refugee row and the state government's announcement to grant Permanent Resident Certificate (PRC) to non-tribal communities residing in the state also kept the state in news during the year.
Chief Minister Pema Khandu and Deputy Chief Minister Chowna Mein's announcement at a public meeting at Namsai had evoked strong resentment among the community based organisations who demanded the state government to take a decision only after submission of a report by a joint high-powered committee constituted under Environment and Forest Minister Nabam Rebia.
The All Arunachal Pradesh Students' Union (AAPSU) while opposing granting of citizenship to Chakma and Hajong refugees made its stand clear on the imbroglio stating that the people of the frontier state would not accept such a move at any cost.
The year also witnessed crisis in the Arunachal Pradesh Public Service Commission (APPSC) following a question paper fiasco in the preliminary examination of combined exams.
With assembly elections due this year, Chief Minister Khandu launched the Arunachal Rising Campaign throughout the state in November to make people aware about all the flagship programme and schemes launched by the Centre and his government.
The law and order scenario in the state during 2018 remained grim with underground elements intensifying extortion bids in Tirap, Changlang and Longding districts.
Security forces also gunned down two hardcore NSCN (K) militants in an ambush in Longding district while more than 24 cadres of NSCN (IM), NSCN (K), NSCN (R) and ULFA were arrested during the year with huge cache of arms and ammunition.
Several murder and rape cases were also reported from the state during 2018.
Over hundred houses have been completely gutted in devastating fire in the state during the year gone by.
Flood and landslides lashed several district in the state causing massive damage to hundreds of dwellings besides snapping power supply and surface communications in several districts.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)