Krishnagiri (kiɾɯʂɳaɡiɾi) is a city in the state of Tamil Nadu, India, and it serves as the administrative headquarters of Krishnagiri District formed in 2004. It is located at the bottom of Krishnadevaraya Hills, and the town is fully surrounded by hill rocks. It is located 250 km from Chennai, 45 km from Dharmapuri, and 90 km from Bengaluru. Krishnagiri is known as "Mango Capital of India" as mangoes are cultivated as the main crop, and the land here is extremely fertile with rich access to fresh water making it amenable to growing crops. Krishnagiri is the site of significant business and residential development. The Krishnagiri Dam was built in 1967.
The Krishnagiri district has a prehistoric importance. Archeological sources confirm the presence of habitats of mankind during Paleolithic, Neolithic and Mesolithic Ages. Various rock paintings and rock carvings of Indus Valley civilization and Iron Age seen in this district support the historical significance of this district.
Krishnagiri region is a part of the ancient Kongu Nadu and Chera country. Historically it was ruled by Chera rulers. Later the region came under Cholas, Pallavas, Gangas, Nulambas, Hoysalas, Vijaya Nagar and Bijapur emperors, Wodeyars of Mysore and Nayaks of Madurai. This region of Krishnagiri served as "Gateway of Tamil Nadu" and the protective barrier for the southern region defending onslaughts from invaders with motives of imperialism and exploitation. Krishnagiri Fort become the first and foremost defensive place. The majestic fortress, built on Krishnagiri hill by the Vijaya Nagar emperors, stands as testimony still now.
During Mysore war I, the British troops passed through Krishnagiri to attack Hyder Ali's Forces at Kaveripattinam. British army was defeated here. In Mysore war II after the "Treaty of Srirangapattinam" entire region of Salem and Barah Mahal were surrendered to the British. In 1792 AD, Captain Alexander Reed became the first District Collector of this region.