Short answers, pulled from the story.
The Rohingya are a stateless Indo-Aryan ethnolinguistic group who predominantly follow Islam and originate from Rakhine State in western Myanmar. They maintain they are indigenous to the region with a heritage of over a millennium, with ancestral roots connected to Arab, Mughal, and Portuguese influences. The Myanmar government disputes this, classifying them as Bengali migrants from Chittagong in Bangladesh.
The Rohingya were rendered stateless by Myanmar's 1982 citizenship law, which denied citizenship to any community not recorded in a British colonial survey conducted in 1823. The law did not list the Rohingya among the 135 recognised national races of Burma, stripping most of the Rohingya population of citizenship in their historical homeland of Arakan.
A study released in August 2018 estimated that more than 24,000 Rohingya were killed by the Myanmar military and local Buddhists since clearance operations began on the 25th of August 2017. Medecins Sans Frontieres calculated that at least 6,700 Rohingya were killed in the first month alone, including at least 1,000 children, with 69% killed by gunshots and 9% burnt to death.
By December 2017, an estimated 625,000 refugees from Rakhine State had crossed into Bangladesh since August 2017. Over 400,000 fled in the first four weeks of the major military operations, representing approximately 40% of the remaining Rohingya population in Myanmar. Since 2015, over 900,000 Rohingya have fled to south-eastern Bangladesh alone.
The term Rohingya likely derives from Rakhanga or Roshanga, historical names for the state of Arakan, meaning roughly "inhabitant of Rohang," which was the early Muslim name for Arakan. The modern term emerged from the colonial and pre-colonial terms Rooinga and Rwangya. British physician Francis Buchanan documented the name in 1799, recording that Muslims settled in Arakan called themselves Rooinga, or natives of Arakan.
The International Criminal Court opened an investigation into crimes against humanity committed against the Rohingya. The International Court of Justice has heard a case alleging genocide. A 2015 Yale Law School assessment concluded that Myanmar's campaign against the Rohingya could be classified as genocide under international law, and the International State Crime Initiative of the University of London issued a report stating that a genocide is taking place.