A group of lawmakers issued a letter to the Department of Homeland Security Secretary Kirstjen Nielsen and Secretary of State Mike Pompeo to cease the deportation of Black Mauritanian nationals, who face the threat of race-based discrimination, violence, or slavery if forced to return to Mauritania located in northwest Africa.

U.S. Senator Kamala D. Harris (D-CA) and Representatives Bennie G. Thompson (D-MS), Jerrold Nadler (D-NY), Zoe Lofgren (D-CA), and Joyce Beatty (D-OH) said the in the bicameral letter that the Mauritanians who aren’t considered citizens will be in grave danger if returned to their homeland.

“Most Mauritanians in the United States arrived here seeking refuge from government-led racial and ethnic persecution and extreme violence,” wrote the lawmakers.

“For the following two decades our government declined to deport Mauritanians because of the dangerous and potentially life-threatening conditions they would face if they were returned to their country of origin.”

There are approximately 3,000 Black Mauritanians in the United States, most of whom arrived in the 1990s after their government forcibly expelled them and stripped them of their citizenship on the basis of their race and ethnicity.

The country known for its modern-day slavery is majority Arab and from the Berber tribe, which has persecuted its minority citizens for simply being black.

So far in Fiscal Year 2018, the Trump administration has deported 79 Mauritanians, up from eight in FY 2017, according to the lawmakers.

“Mauritanians deported from the United States face unacceptable threats of racial and ethnic discrimination and slavery…We ask DHS and the State Department to jointly respond within 60 days to the following questions to clarify U.S. policies and practices regarding deportations of Mauritanians.”