Short answers, pulled from the story.
The Rohingya are an Indo-Aryan ethnic group who have long settled in Arakan, with some historians claiming descent from Arab merchants and early Muslim settlements dating to the 7th century. The term Rohingya emerged from pre-colonial terms like Rooinga and was adopted by Bengali Muslim intellectuals in the 20th century.
British policy encouraged Bengali inhabitants to migrate into Arakan as farm labourers during the early 19th century, leading to thousands settling in the region between 1815 and 1936. Immigration peaked in 1927 when 480,000 people arrived, making Rangoon the greatest immigration port in the world at that time.
The 1982 Citizenship Act denied citizenship rights to the Rohingya because they were not listed among the 135 national races recognized by the Burmese military junta. This law made much of the Rohingya population stateless in their historical homeland of Arakan and served as a legal foundation for subsequent human rights violations.
A study estimated more than 24,000 Rohingya people were killed since the clearance operations began on the 25th of August 2017, while over 400,000 refugees fled to Bangladesh within the first four weeks of the conflict. By December 2017, an estimated 625,000 refugees had crossed into Bangladesh from Rakhine state.
International organizations classify the treatment as ethnic cleansing or genocide due to evidence of summary executions, enforced disappearances, arbitrary arrests, torture, and forced labour conducted by Myanmar security forces. The United Nations reported that these actions amount to crimes against humanity and included widespread indiscriminate attacks targeting civilians including women and children.