The diocesan territory of 11,298 square kilometers covers four districts of Bhojpur, Buxar, Kaimur and Rohtas in the southwestern part of Bihar state, known as the Shahabad region. The flat alluvial bed of the Ganges spreads along the upper half of the territory in northern Bhojpur and Buxar.
Total population is 7,985,362.
Hindi, Urdu and the Bhojpuri dialect are in use.
When Patna diocese was established in 1919, its territory included all of what was then central and north Bihar, besides Nepal. With the arrival and management of the Jesuit missionaries, the local Church grew both in numbers and institutional structures. They founded many Christian communities, leading to the creation of new dioceses. By the time Patna was made an archdiocese in 1999, it had given birth to four new dioceses: Bhagalpur (1956), Muzaffarpur (1980), Bettiah (1998) and Purnea (1998). Additionally, Nepal had been separated as an independent mission in 1983. The creation of yet another diocese, Buxar, in 2000 testifies to the continuing growth of the Christian community in Bihar.
The first Christian presence in the Buxar diocesan area seems to date back to 1887, when the Methodist Episcopal Church was founded. Baptists later established some centers, including the Sawtelle Memorial High School (1918) and a hospital.
Invited by some Protestant converts to Catholicism, missionaries from Patna established the first mission in Shahabad in 1937, at Ara. Other mission centers followed and Christian communities grew around them, especially in Piro, Shahpur, Buxar, Dumraon, Itarhi, Chenari, Koath, and Sasaram. As the number and size of the these communities increased, Church institutions and organizational structures grew with them, leading to significant socio-cultural change among the majority Dalit (formerly called "untouchables") Christians of the area.
Over the past 60 years, the Catholic presence in the area has been visible not only in Church's physical infrastructure, such as churches, institutions, etc., but more importantly in and through the members of the Church: laity, clergy and religious. Due to lack of development in the region and few employment opportunities, many Christians migrated to cities. Buxar diocese was created to enhance the building of a strong Christian community in Shahabad.
The diocesan territory straddles the states of Bihar and Jharkhand, which was created from Bihar in 2000. Executive and legislative powers are vested in elected representatives.
Under the Panchayat Raj rule, elected representatives of a panchayat monitor development work in the village.
Railway, bus, vans, tempo (passenger jeeps or motorized tricyles) and taxis are the means of transport.
Agriculture is the main occupation of the local people, who grow sugar cane, tobacco, rice, lentils and wheat as major crops. Production of oil is also a major industry.
All India Radio broadcasts in the diocesan area.
Rohtas and Bhojpuri have the second- and fourth-highest literacy rates in Bihar, respectively, at 62.36 percent and 59.71 percent. The rate for Buxar is 57.49 percent and for Kaimur 55.57 percent.
The average litercay rate in Bihar is 47.5 percent.
A majority of the local people can be identified primarily as belonging to Hindu caste groups. Other identifiable groups include Anglo Indians, Bengalis, Pathans, South Indians, and Shia Muslims of non-Indian origin in particular. Christians form a separate group, though they originally belonged to Hindu castes. The vast majority of Christians of the region are Dalits.