Title: Political integration of India
Content:  Bihar with effect from 1 January 1948. Later that year, 66 states in Gujarat and the Deccan were merged into Bombay, including the large states of Kolhapur and Baroda. Other small states were merged into Madras, East Punjab, West Bengal, the United Provinces and Assam. Not all states that signed Merger Agreements were integrated into provinces, however. Thirty states of the former Punjab Hill States Agency which lay near the international border and had signed Merger Agreements were integrated into Himachal Pradesh, a distinct entity which was administered directly by the centre as a Chief Commissioner's Province, for reasons of security. The Merger Agreements required rulers to cede 
Title: History of Bihar
Content:  Under the British Raj, Bihar particularly Patna gradually started to attain its lost glory and emerged as an important and strategic centre of learning and trade in India. From this point, Bihar remained a part the Bengal Presidency of the British Raj until 1912, when the province of Bihar and Orissa was carved out as a separate province. When the Bengal Presidency was partitioned in 1912 to carve out a separate province, Patna was made the capital of the new province. The city limits were stretched westwards to accommodate the administrative base, and the township of Bankipore took shape along the Bailey Road (originally spelt as Bayley Road, after 
Title: Central Provinces and Berar
Content:  India became independent on 15 August and the Central Provinces & Berar became a province of the Dominion of India. The princely states, which were under the Central Provinces before 1936, were merged into the province, and organized into new districts. When the Constitution of India went into effect in 1950, the Central Provinces & Berar was reorganized with territorial changes as the state of Madhya Pradesh, which name also means Central Province. On 1 November 1956, Madhya Bharat, together with the states of Vindhya Pradesh and Bhopal State, was merged into Madhya Pradesh. In 1956, strong demand due to linguistic similarity from Marathi Irredentists, the Berar and Nagpur divisions were transferred to Bombay State. In 1960, the Bombay State was partitioned into Maharashtra & Gujarat. In 2000, the eastern portion of Madhya Pradesh was split off to become the new state of Chhattisgarh.
Title: West Bengal
Content:  When India gained independence in 1947, Bengal was partitioned along religious lines. The western part went to the Dominion of India and was named West Bengal. The eastern part went to the Dominion of Pakistan as a province called East Bengal (later renamed East Pakistan in 1956), becoming the independent nation of Bangladesh in 1971. In 1950 the Princely State of Cooch Behar merged with West Bengal. In 1955 the former French enclave of Chandannagar, which had passed into Indian control after 1950, was integrated into West Bengal; portions of Bihar were also subsequently merged with West Bengal. Both West 
Title: Berar Division
Content:  Central Provinces as the 'Berar Division'. On 24 October 1936, with the establishment of the legislative assembly of the 'Central Provinces and Berar' the Central Provinces became 'Central Provinces and Berar' when it was fully merged with Berar, although Berar Division remained under the nominal sovereignty of Hyderabad. Following the independence of India in 1947, the Central Provinces and Berar became a province of India, and in 1950 became the Indian state of Madhya Pradesh. In 1956, the Indian states were reorganized along linguistic lines, and Berar and Nagpur became part of Bombay state. In 1960, Bombay state was split along linguistic lines, and the southern, Marathi-speaking portion of the state, including Berar Division, became the new state of Maharashtra.
Title: History of West Bengal
Content:  In 1950, the Princely State of Koch Bihar merged with West Bengal after King Jagaddipendra Narayan had signed the Instrument of Accession with India. In 1955, the former French enclave of Chandannagar, which had passed into Indian control after 1950, was integrated into West Bengal. Portions of Bihar were subsequently merged with West Bengal. During Roy's Chief Minister-ship very few manufacturing industries were set up in the state. In 1954, when Dr. B. C. Roy was the Congress chief minister, a massive food crisis overtook the state. There was a near-famine condition in Bengal.
Title: Administration in Bihar
Content:  Before 1905, Bihar was a part of British East India Company's Bengal Presidency. In 1905 the Bengal Presidency was divided and created two new provinces: East Bengal and West Bengal. Until then Bihar was part of West Bengal. Again West Bengal and East Bengal reunited in 1911 but the people of Bihar and Orrisa demanded a separate province based on language rather than religion. In 1912 Bihar and Orissa Province was created separating from Bengal Presidency. In 1936, Bihar and Orrisa Province divided into two new provinces: Bihar Province and Orissa Province.
Title: Hazaribagh
Content:  split from Bengal Province. In 1936, the province was split into separate provinces of Bihar and Orissa, with the Chota Nagpur Division being a part of Bihar. Bihar's boundaries remained mostly unchanged after Indian Independence in 1947. Giridih district was created in 1972 by carving some parts of Hazaribagh district. After the 1991 census, the district of Hazaribagh was divided into three separate districts, Hazaribagh, Chatra and Koderma. The two sub-divisions Chatra and Koderma were upgraded to the status of independent districts. In 2000, Jharkhand was separated from Bihar to become India's 28th state. In 2007, Ramgarh was separated and made into the 24th district of Jharkhand.
Title: Birender Singh (politician, born 1921)
Content:  When India became independent in 1947, the old province of Punjab was partitioned and East Punjab was retained by India. Several Princely states located on the plains of East Punjab were merged to create the state of PEPSU. Several other princely states in the hills of East Punjab were similarly merged to create the Chief Commissioners' Province of Himachal. The portion which had been directly ruled by the British (rather than by the Maharajas of various princely states) became a third, separate state and received the name Punjab. The Ahirwal region and Rewari lay within this state of Punjab (India), and Birendra Singh was a minister in this state. In the period 1956–66, the three political entities described above were merged and de-merged so that finally, in 1966, the 
Title: History of Bihar
Content:  of India. The Pala Empire also made their capital at Pataliputra once during Devapala's rule. After the Pala period, Bihar played a very small role in Indian history until the emergence of the Suri dynasty during the Medieval period in the 1540s. After the fall of the Suri dynasty in 1556, Bihar again became a marginal player in India and was the staging post for the British colonial Bengal Presidency from the 1750s and up to the war of 1857–58. On 22 March 1912, Bihar was carved out as a separate province in the British Indian Empire. Since 1947 independence, Bihar has been an original state of the Indian Union.

Question: when did bihar bifurcate from bengal and some parts of chota nagpur merged into bengal?
Answer: 1912.