Answer:
Yemen is anything but a desired country by the immigrants, it's one of the poorest countries in the world, the government doesn't give any protection to the immigrants and there's an ongoing military conflict in the country. Most of the immigrants are from Ethiopia (around 85%), and there are two reasons for the surprisingly big number of them coming to Yemen.
1. Almost all of them use Yemen as a stepping stone towards Saudi Arabia, which started taking Ethiopian migrants tactically again, as it is in need of a work force, and Ethiopians are very cheep workers.
2. Very few go to Yemen and stay in there as mercenaries. Usually those are people with criminal or military service background. They get better paid, so they see the conflict as a work place (as weird as it sounds).
