|c. 20 million|
|Regions with significant populations|
|Urdu, various Bihari languages|
|Related ethnic groups|
Bihari Muslims are adherents of Islam who identify linguistically, culturally, and genealogically as Biharis. They are geographically native to the region comprising the Bihar state of India, although there are significantly large communities of Bihari Muslims living elsewhere in the Indian subcontinent due to the Partition of British India in 1947, which prompted the community to migrate en masse from Bihar to East Pakistan.
Bihari Muslims make up a significant minority in Pakistan under the diverse community of Muhajirs (lit. 'migrants'), and largely began arriving in the country following the Bangladesh Liberation War of 1971, which led to the secession of East Pakistan from the Pakistani union as the independent state of Bangladesh. Since 1971, Bihari Muslims residing in Bangladesh are widely referred to as Stranded Pakistanis in Bangladesh who are awaiting repatriation to Pakistan, and have faced heightened persecution in the country due to their collaboration with West Pakistani forces in perpetrating the 1971 Bangladesh genocide against Bengalis and Hindus.
The majority of Bihari Muslims adhere to the Sunni branch of Islam, and the adoption of the religion by Biharis traces back to the 14th century, when Afghan traders and Sufi missionaries began to arrive in the region a century prior to the Mughal Empire's conquest of the subcontinent. There are also a significant minority of Biharis who adhere to the Shia branch of Islam, largely residing in Patna and Gopalpur tracing their religious descent to Shia Muslim settlers from Lucknow who arrived in the region in the 19th century.
The large-scale arrival of Muslims in Bihar began in the 14th century, when Afghan traders and Sufi saints-warriors settled in the South Bihar plains and furthered the process of agricultural colonisation while also spreading Islam among the local populace. Muslims were not the only new immigrants to Bihar during this period. Inscriptions in Bihar Sharif tell of a Sufi warrior by the name of Malik Ibrahim Bayu who came to Bihar and defeated the non-Hindu Kol tribe who had been oppressing the local Muslims. He conquered many Kol chiefdoms.
Some of the kings and chieftains of medieval Bihar were Muslim. The chieftaincy of Kharagpur Raj in modern-day Munger district was originally controlled by Hindu Rajputs. In 1615 after a failed rebellion by Raja Sangram Singh, his son Toral Mal converted and he changed his name to Roz Afzun.
The Faujdars of Purnea (also known as the Nawabs of Purnea) created an autonomous territory for themselves under the leadership of Saif Khan and ruled in parts of Eastern Bihar in the early 1700s. They were engaged in a protracted conflict with the neighbouring Kingdom of Nepal.
Many Bihari Muslims migrated to Pakistan and Bangladesh (then East Pakistan) after independence in 1947.
Bihari Muslim society has traditionally been divided by caste and clan affiliations. Muslims refer to these distinctions as biraderi and they are not as rigid as those followed by Hindus, but intermarriage remains rare. The Ashraf groups are equivalent to upper castes  and include groups like Pathans, Sayyid, Sheikh, Mallick and Mirza. The Pathans of Bihar are mostly the descendants of Pashtun settlers with some being descended from local high-caste Bhumihar and Rajput converts. The Mirzas claim descent from the Mughals and are found mainly in the area around Darbhanga and Muzzafarpur. Among the largest Ajlaf groups are the Ansaris who form 20% of the Muslim population in Bihar. Their traditional occupation is weaving.
The following table shows the Muslim population of Bihar by district:
|Number||District||Population (2001)||Muslim population||Percentage|
Sum total of this table is 14,780,500 Muslims out of 83.0 million total population in 2001 census, hence Muslims were 16.5% of total population in Bihar. In 2011 census, total population grew to 103.9985 million, of which 16.9% or 17,557,809 were Muslims. During 2001–2011, Muslims grew by 33.433%, while non-Muslims grew by 23.537%. District-wise break up by religions for 2011 is not available.Kishanganj is the only district in Bihar, which is Muslim majority district.
In common with the rest of India, the Muslims in Bihar are largely descendants of native converts from various castes. The rise of the Indian Muslim population can be traced back to the early 12th century, with many conversions to Islam taking place during the rule of the Sur Empire, which had established its capital in Sasaram.
Abdul Kadir Khanzada, who represents Orangi Town in Pakistan's parliament, said he would like to welcome Nitish to his constituency, where a majority of over a million people have their roots in Bihar.
According to local NGOs working for Bihari welfare, around 400,000 members of the community live in camps in Bangladesh.
Approximately 240,000 Bihari Muslims live in various camps around the country; they have remained in the country since 1971 awaiting settlement in Pakistan. Biharis are non-Bengali Muslims who emigrated to what was formerly East Pakistan during the 1947 partition of British India. Most supported Pakistan during Bangladesh's 1971 war of independence. They later declined to accept Bangladesh citizenship and asked to be repatriated to Pakistan. The Government of Pakistan historically has been reluctant to accept the Biharis. During a visit to Dhaka in January, the Pakistani Prime Minister announced that Pakistan would be willing to assist in their repatriation, but no repatriation occurred during that year.