Several groups of people have claimed lineal descent from the Israelites (or Hebrews), an ancient Semitic-speaking people who inhabited Canaan during the Iron Age. The phenomenon has become especially prevalent since the founding of the State of Israel in 1948. The country's Law of Return, which defines Jewishness for the purpose of aliyah, prompted many individuals to claim Israelite ancestry with the expectation that it would make them eligible for Israeli citizenship. The abundance of these claims has led to the rise of the question of "who is a Jew?" in order to determine the legitimacy of one's Jewish identity. Some of these claims have been recognized, while other claims are still under review, and others have been outright rejected.
There were numerous events in Jewish history that forced the Jewish people into exile from the Land of Israel, compelling them to disperse throughout many of the world's regions. The most significant of these events are recorded in the Hebrew Bible, but have been attested by extra-biblical evidence as well. The most notorious exilic occurrences were: the fall of the Kingdom of Israel to the Neo-Assyrian Empire in c. 720 BCE; the fall of the Kingdom of Judah to the Neo-Babylonian Empire in c. 586 BCE; the Roman siege of Jerusalem in 70 CE; and the Bar Kokhba revolt in the 130s CE. A number of these communities of the Jewish diaspora came into existence (sometimes voluntarily) as a result of Israelites and Jews emigrating before the onslaught of invading armies; because of forced deportations; or because of enslavement, including the Assyrian captivity and the Babylonian captivity. Some Jewish families or even some whole Jewish communities were forced to relocate on a near-consistent basis because of anti-Jewish persecution, while many were wiped out entirely. Although some form of contact had been maintained between most of the mainstream Jewish diaspora communities over the millennia, contact had been lost with some of them, and as a result, they came to be regarded as lost by mainstream Jewry.
