Chainpur lies in the hilly tracts of Kaimur district.

Chainpur is a rural block with no major urban centres. The block's sex ratio in 2011 was 939 females for every 1000 males, which was the highest sex ratio in Kaimur district (the district-wide ratio was 920). The sex ratio was higher in the 0-6 age group, where it was 968 (the district-wide value was 942). Members of scheduled castes made up 20.06% of the block population and members of scheduled castes made up 4.87%. The block's literacy rate was 62.53%, compared to the district-wide average of 69.34%. There was a 21.79% gender literacy gap (compared with the district-wide 20.97%), with 73.04% of men but only 51.25% of women able to read and write.

Most of the Chainpur block workforce in 2011 was employed in agriculture, with 18.52% being agricultural labourers who owned or leased their own land and another 58.78% being agricultural labourers who worked someone else's land for wages. Another 6.31% worked in household industries, and the remaining 16.39% were other workers. Men made up around two-thirds of the block workforce, with there being 43,681 male and 20,795 female workers in 2011.

In Chainpur is the mausoleum of Bakhtiar Khan, the son-in-law of Sher Shah Suri. The town was originally established by, the desendants of Diwan Rao, a son Of Raja Dham Dev. There is also the Hindu shrine of Harsu Brahm. According to the shrine's tradition, the Kanyakubja Brahmin priest Harshu Pandey, who was in the service of Raja Shaliwahan, committed suicide in protest of the demolition of his house, but when his body was cremated at Varanasi, he was seen miraculously standing as if still alive. The family of Chainpur became immensely powerful during Mughal empire. Chainpur was made a jagir during Mughals and a fort name as "Chainpur ki rani ka kila" was made by the family. The family of Chainpur became immensely powerful during Mughal empire. Chainpur was made a jagir during Mughals and a fort name as "Chainpur ki rani ka kila" was made by the family. They had better relationship with the zamindar families of Kamsar. Before even Bhabua came under the Jagir of Chainpur and was a small group of villages primarily established by Akhlash Khan of Ikhlashpur wo was a governor of Bihar during Shahjahan. It was Akhlash Khan who made Malik wishal Khan a Faujdar and Kiladar of Rohtas garh. The jagir had two Parganas name as Bhabua and Mohania. The family of Chainpur, Mohania, and Bhabua was also established by the descendants of Dham Dev Rao a Sakarwar king, who later came down to Ghazipur and their descendants established many villages. His elder brother was Kam dev who descendants established Sherpur, Reotipur (Dalpatpur), Dildarnagar Kamsar and many other places in Ghazipur and Bihar. From the same place belonged Raja Deendardar Khan of Dildarnagar, During Mughal empire and early British era descendants of Dham Dev and Kam Dev ruled a very large part of Ghazipur district, Rohtasgarh, Kaimur region, and Chausa in Buxar.

Chainpur block contains the following 177 villages, of which 151 are inhabited and 26 are uninhabited: