Coal mines Of Dhanbad(Reality)

There are a one city in jharkhand which is name is Dhanbad, it is coal field area, it is situated at jharkhand but few year ago it is in State in Bihar, but in 2000 year it was saprated from bihar and became new state jharkhand. That is not any story but it is reality of Dhanbad land.when dhanbad was part of bihar there are so many coal mines operated and so many people was working there