Country of Origin: Sudan. Location: Washington area.

Alaaeldin M. Ahmed’s grocery store in the nation’s capital is about a 10-minute drive from the White House, and it sometimes seems that he could not have picked a better spot to sell halal meats, rice and spices to Sudanese expatriates.

“They love to be in capitals,” Mr. Ahmed, who came to the United States from Sudan in the early 1990s, said of his countrymen on Monday. “I don’t know exactly why.”

Perhaps, Mr. Ahmed added with a chuckle, it is because the Washington area can feel “exactly like Khartoum.” (Khartoum is the capital of Sudan, which is covered by Mr. Trump’s order; South Sudan, which became independent in 2011, was not affected.)

Washington and its suburbs have a larger Sudanese population than any other metro area in the United States, which has long drawn Sudanese seeking to escape their native country’s political strife. Still, census figures show a population of only 4,621 foreign-born Sudanese in Washington and its suburbs and exurbs. The population is dispersed with many living in suburbs like Alexandria, Va. But it is a close-knit community in times of crisis.

“If somebody passes away in the Sudanese community, you’ll find hundreds of Sudanese going to the funeral,” said Ahmed M. Elhillali, a Sudanese lawyer who has practiced in Washington for more than 20 years.