Uttar Pradesh covers a large part of the densely populated plains around the Ganges. With 166 million inhabitants, it is not only the most populous state in India but also the most populous subnational entity in the world. Only 5 countries of the world have a higher population than Uttar Pradesh (see List of countries by population). It is also one of the most economically backward states of India.
It covers the area of the old princely state of Oudh.