Weeks before Sudan flamed into a calamitous civil war, one of the richest men in the Middle East, Sheikh Mansour bin Zayed al-Nahyan, welcomed an architect of the chaos to his sumptuous Persian Gulf palace. The sheikh, a younger brother to the powerful ruler of the United Arab Emirates, is recognized in the West as a collector of superyachts and racehorses, and is perhaps best known as the owner of Manchester City, the hugely successful English soccer team. Last year, his team in New York won approval to build a $780 million soccer stadium in Queens, the first in the city. Yet there he was, in February 2023, openly entertaining a notorious commander from the deserts of western Sudan — someone who had seized power in a coup, built a fortune on illicit gold and was accused of widespread atrocities.