Gypsies and Jews were extreme emigrators. They suffered genocide.
Gypsies emigrated from India 1000 years ago. Jews emigrated from Israel and Palestine 2000 years ago. Both of them died in large numbers at the hands of Foreigners over 1000s of years.
I think this may not be just a lonely datapoint. It is possible that there are safeguards in evolution against excessive immigration and excessive emigration in tribes.
Disintegrated tribes failed and integrated tribes succeeded partly due to the qualities of its members. It is possible that immigration from disintegrated tribes affects the systemic qualities of integrated tribes which made them successful.
Muslims are emigrating from their disintegrated tribes in large numbers and upsetting the well being of integrated tribes. This may lead to genocides over a millennia.
Already bombing of mosques in France is at all time high.