Abia State () is a state in the South-East geopolitical zone of Nigeria, it is bordered to the north and northeast by the states of Enugu, and Ebonyi, Imo State to the west, Cross River State to the east, Akwa Ibom State to the southeast, and Rivers State to the south. It takes its name from the acronym for four of the state's most populated regions: Aba, Bende, Isuikwuato, and Afikpo (but Afikpo was later joined with a part of Enugu state to create Ebonyi state in 1996). The state capital is Umuahia while the largest city and commercial centre is Aba. Abia is the 32nd largest in area and 27th most populous with an estimated population of over 3,720,000 as of 2016. Geographically, the state is divided between the Niger Delta swamp forests in the far south and the drier Cross–Niger transition forests with some savanna in the rest of the State. Other important geographical features are the Imo and Aba Rivers which flow along the Abia's western and southern borders, respectively. Modern-day Abia State has been inhabited for years by various ethnic groups, but it is predominantly inhabited by the Igbo people. In the pre-colonial period, what is now Abia State was a part of Arochukwu-based Aro Confederacy before the confederacy was defeated in the early 1900s by British troops in the Anglo-Aro War. After the war, the British incorporated the area into the Southern Nigeria Protectorate which later merged into British Nigeria; after the merger, Abia became a centre of anti-colonial resistance with the Women's War that started in Oloko. After independence in 1960, the Abia was a part of the post-independence Eastern Region until 1967 before the region was split and it became part of the East Central State. Less than two months afterwards, the former Eastern Region attempted to secede in the three-year long Nigerian Civil War with Abia as a part of the secessionist state of Biafra. At the war's end and for the reunification of Nigeria, the East Central State was merged as one until 1976 when Imo State](including now-Abia) was formed by the Murtala Muhammed regime. Fifteen years afterwards, Imo State was divided with eastern Imo being broken off to form the old Abia State; but in 1996, part of Abia's northeast was removed to form a part of the new Ebonyi State. Economically, Abia State is based around the production of