Violence against Muslims is frequently in the form of mob attacks on Muslims by Hindus. These attacks are referred to as communal riots in India and are seen to be part of a pattern of sporadic sectarian violence between the majority Hindu and minority Muslim communities, and have also been connected to a rise in Islamophobia throughout the 20th century. Most incidents have occurred in the northern and western states of India, whereas communalist sentiment in the south is less pronounced. Among the largest incidents were Great Calcutta killings in 1946, Bihar and Garmukhteshwar in 1946 after Noakhali riot in East Bengal, the massacre of Muslims in Jammu in 1947, large-scale killing of Muslims following the Operation Polo in Hyderabad, anti-Muslim riots in Kolkata in the aftermath of 1950 Barisal Riots and 1964 East-Pakistan riots, 1969 Gujarat riots, 1984 Bhiwandi riot, 1985 Gujarat riots, 1989 Bhagalpur riots, Bombay riots, Nellie in 1983 and Gujarat riot in 2002 and 2013 Muzaffarnagar riots.