Such forcible removals often involve the use or threat of violence to intimidate people into leaving their homes, and in some cases there are no records of exactly how many died or disappeared in the process. Therefore ethnic cleansing can border on or even be a precursor of Genocide.
As a euphemism for genocide it was used by Adolf Hitler and the Nazis during World War II as a propaganda smokescreen. They claimed to be resettling Jews in the East when in reality they murdered six million Jews and seven million disabled people, homosexuals, gypsies, black people, and political opponents. Also ethnic cleansing was one of the reasons why Kosovo declared independence from Serbia.