The Hebrew Israelite issue is a demonstration of how complete and unfounded wannabism can be turned into a reality.
Towards the end of the 19th century some African-Americans churches who previously had identified themselves with the ancient Hebrews shifted into an identification as ancient Hebrews. This movement gave birth to various groups, mostly clear Christian denominations and others that mix Jewish and Evangelical elements in their worship. The Commandment Keepers founded by Wentworth A. Matthew, for example, adopted mostly traditional Jewish worship and lifestyle and kept cordial ties with the mainstream Judaism.
While the Commandment Keepers viewed the non-black Jews as those who preserved Judaism over the centuries many of the present-day Hebrew Israelites accuse the rabbinic Jews of being white impostors. The Anti-Defamation League has accused some groups of promoting black supremacy.
Ben Carter, later to be known as Ben Ammi Ben-Israel, founded the African Hebrew Israelites of Jerusalem in Chicago in 1966 and moved in 1969 with a group of 30 adherents to Israel. About 600 members have moved after them to Israel where the community in Dimona now counts ca. 2,500 members and reveres Ben-Israel as their "messiah".
Many of them clearly state that they are "Hebrews" or "Israelites" as opposed to traditional Jews. It is unclear up to what extent they follow the New Testament. However they completely deny the authority of the Jewish Oral Law.
Some members of the Hebrew Israelite community in Dimona have converted to Judaism, it is unclear to me what their status is in their strictly closed community after the gijur. The general acceptance of the Hebrew Israelites among the Israeli public has improved and now they even serve in the IDF. However, their Jewish status is clearly denied.
The "Israelite" elements in the H-I religion obviously date back no further than to the times of conversion to Christianity of their ancestors after being transferred to America from western Africa. They cannot prove any pre-existing linguistic, religious or cultural connection to Judaism whatsoever like what you can find in the case of the crypto-Jews' and their descendants.