Ranchi district is one of the twenty-four districts of Jharkhand state in eastern India. Ranchi city, the capital of Jharkhand state is the district headquarters. It was established as a district in 1899.As of 2011 it is the most populous district of Jharkhand (out of 24).

The geographical area now comprising Ranchi district was formerly part of old Lohardaga district of the British India. In the year 1831-32, a part of old Lohardagga district was carved out and given the name of the Non-regulation South-West Frontier, and in 1899 the name of the district was changed to Ranchi district. Ranchi was the name of a type of bird seen in the local mountain temple.

The geographical area currently comprising the district of Ranchi was ruled by the Kshatriya rulers named hanimukut and was in the direct control of the kings of the epic period of the Mahabharata such as Jarasandh, the king of Rajgir. However Lord Krishna was believed to have a loose control over the territory.

Magadha Empire exercised indirect control over the territory, which lasted until the reign of the Ashoka. Kalinga rulers are believed to have ravaged the region during their expeditions to Rajgir and Pataliputra. Armies of Samudra Gupta passed through the region on their expedition to Deccan. After the decline of the Guptas, Phanimukut established the Kingdom of Chhotanagpur. The legendary Phanimukut, which literally means the crown of the cobra, was found by the side of a cobra (Nag in Hindi), and grew to be an industrious king, and founded the Nag Dynasty, which ruled Ranchi district and a larger part of Chota Nagpur Plateau as a sovereign king for almost next 1000 years.

With the expansion of the Mughal Empire, the sovereign status of the Nag Dynasty was technically affected, but they continued to rule and administer independently until the advent of the East India Company. During the period of the British Raj, adivasis and the local population of other ethnic backgrounds of Ranchi and other regions currently comprising the State of Jharkhand continued to oppose the subjugation by the British, and the region witnessed a number of uprisings and revolts.

In 2006 the Indian government named Ranchi one of the country’s 250 most backward districts (out of a total of 640). It is one of the 23 districts in Jharkhand currently receiving funds from the Backward Regions Grant Fund Programme (BRGF).

According to the 2011 census Ranchi district has a population of 2,912,022, roughly equal to the nation of Jamaica or the US state of Arkansas.This gives it a ranking of 130th in India (out of a total of 640).The district has a population density of 557 inhabitants per square kilometre (1,440/sq mi).Its population growth rate over the decade 2001-2011 was 23.9%.Ranchi has a sex ratio of 950 females for every 1000 males, and a literacy rate of 77.13%.