The Pale of Settlement

The Pale of Settlement was a term used by the Russian Empire. It meant the borders in which permanent residency by Jews was allowed (from 1791 to 1917). Beyond these places, Jewish residency, permanent or temporary, was mostly forbidden.
The old English term "pale" is got from the Latin word "", a stake, and so extended to mean the area enclosed by a fence or boundary.
The Pale of Settlement included all of modern Belarus, Lithuania and Moldova, much of Ukraine and Poland, and small parts of Latvia and the western Russian Federation.
It extended from the eastern "pale", or demarcation line inside the country, westwards to the Imperial Russian border with the Kingdom of Prussia (later the German Empire) and Austria-Hungary. It was about 20% of European Russia.
Historians argue that the motivations for its creation and maintenance were primarily economic and nationalist in nature.
The end of the enforcement and formal demarcation of the Pale coincided with the beginning of World War I in 1914 and then ultimately, the fall of the Russian Empire in the February and October Revolutions of 1917.
The religious nature of the edicts creating the Pale is clear: conversion to Russian Orthodoxy, the state religion, released people from the restrictions. Historians argue that the motivations for its creation were mainly economic and nationalist in nature.
Terrible anti-Jewish pogroms occurred from 1881 to 1883 and from 1903 to 1906. The Jewish community responded by organising a welfare system.
One consequence of the Pale was a tendency to restrict marriage by Jews, not just to other Jews, but often in practice to those who attended the same synagogue. The effects are similar to those of the Royal Families of Europe, who eventually showed the genetic effects of inbreeding even though the marriages were legal and in other ways quite appropriate. Just as in European royalty, the communities behind the Pale, and now in normal life, show a higher percentage of deleterious genetic defects than the wider population. This is because the parents were, unknowingly, to some extent consanguineous (related).