Dhanbad was originally a part of Manbhum District which was first in Bengal and then in 1911 it was separated from Bengal and became a part of Bihar-Orissa province. H. Coupland, I.C.S. Published the first District Gazetteer for Manbhum in 1911. The “Preface” of the Gazetteer is reproduced below (without any correction) :
Dhanbad was then only a Subdivision of Manbhum District in Bengal (undivided). The Headquarters town was then known as D H A N B A I D. Later in 1911, when Manbhum became part of Bihar-Orissa province, Dhanbad Subdivision was raised to the status of a Sub-District and named as DHANBAD by dropping the “I” from DHANBAID.
In 1956, on re-organization of the states, the Sub-District Dhanbad was carved out of Manbhum District while the other portion of Manbhum District became part of West Bengal as Purulia District.
Those days, districts in India were much larger in area. The present day distrct of Dhanbad, and at least some part of Bokaro district which was carved out of Dhanbad and Giridih, was also part of Manbhum.
Gazzeteer of India, Bihar, Dhanbad
“This is the first Gazetteer for Dhanbad district. Dhanbad was a part of Manbhum district which was first in Bengal and then came over to Bihar when Bihar was separated from Bengal. when H.Coupland, I.C.S., published the first District Gazetteer for Manbhum in 1911, Dhanbad was only a subdivision of Manbhum district in Bengal. The headquarters town was then known as Dhanbaid. Later when Manbhum was a district in Bihar, Dhanbad subdivision was raised to the status of a sub district and the letter ¢i¢ in the name of the headquarters station was dropped.
As a result of the recommendation of the states Reorganisation Commission, the district of Dhanbad
was carved out in 1956 and remained in Bihar while the other portion of Manbhum district went over to West Bengal.”
This is compiled from various sources from Internet, Wikipedia etc. Any suggestion for addition, deletion, alteration for improvement of the article will be welcomed and acknowledged with thanks.