Between 1977 and 1984, 4,000 Ethiopian Jews immigrated to Israel through the secret operation; most were from Tigray and Wolqayt, while some came from the Gondar area. They left the camps in the middle of the night dressed in dark clothing, arriving at the pick-up points, from which they continued on to the Sudanese coast or a port. There, Mossad agents and naval officers waited for them, and transferred the immigrants to airplanes or ships. The first stop in Israel was Eilat and from there they went on to absorption centers around the country.
Because of the increasing dangers in the camps in Sudan, it was decided to find ways to bring the whole community to Israel. Operation Moses, which began in November 1984 and ended in January 1985, airlifted 6,500 Ethiopian Jews to Israel, most of who came from the Gondar area.
Aliya through Sudan was secret, and its details were known only to a few senior Sudanese officials, and Ethiopian Jews were not permitted to expose their Jewish identity. The operation came to a premature ending following a leak by a public figure in Israel to the press regarding the secret Aliya of Ethiopian Jews to Israel through Sudan. Thousands of Jews were left stranded; many died of hunger and disease in the camps in Sudan, some traveled back to Ethiopia and some remained in Sudan. Others, who had not heard that the gates from Sudan had closed, came to Sudan and were then forced to return to Ethiopia.
In the following year, a number of smaller operations brought Jews who had remained in Sudan and Ethiopia to Israel including Operation Joshua, which was conducted by the U.S Air Force, and brought 494 Jewish refugees remaining in Sudan to Israel.

From the Israel Assocation for Ethiopian Jews website.