While the lineages of the last few Umayyad caliphs in al-Andalus vanished into obscurity, there is at least one case of claimed descent from the Umayyads in Spain at a later date. In 1568, a gathering of crypto-Muslims ('Moriscos', those who had nominally accepted the forced conversion to Catholicism in 1502 but continued practicing in secret) acclaimed one Fernando de Válor as king of Granada, under his Muslim name of Aben Humeya (ibn Umayya). We have good reason to be suspicious of whether he really could trace his descent to the Umayyads, since the Nasrid dynasty of Granada had never used Umayyad ancestry as part of their genealogy. Even during what we call the Umayyad Caliphate of the West, the dynasty there actually called themselves the Banu Marwan (Marwanids, after the branch of the Umayyads who ruled as caliphs 684-750). Aben Humeya's rebellion was defeated by the Spanish forces in a few years despite support from North Africa.

There are quite a few accounts of descendants of the Umayyads of the east, some more plausible than others. The idea of a wholesale slaughter of the clan by the Abbasids is an exaggeration, as many members survived and some even worked as officials in the Abbasid state. The Marwanid lineage was the focus of the killings at Nahr Abi Futrus and other purges also discriminated based on relation to the Marwanids, power, and accessibility.

Upper Egypt was something of a Marwanid power base, and it's there that Marwan II retreated to in 749 CE during the war with the Abbasids. We have records of some Marwanids there being captured after the caliph's death and sent to Palestine for execution, but then later we find a Dihya bin Mu'assab bin al-Asbagh bin 'Abd al-Aziz who revolted against the Abbasids in 761 and 785 CE, the latter attempt ending in his execution. A judge who died in 864, al-Harith bin Miskin bin Marwan (thus the grandson of the caliph) was said to be proud of his Umayyad nisba. He was briefly imprisoned for refusing to make a demonstration of loyalty to the Abbasids and the Mu'tazili doctrine; he conceded and came out alive.

We can go even further forwards in time and still find plausible Umayyad descendants. Describing the tribes of Upper Egypt, the genealogist al-Hamdani informs us that many subgroups of the Umayyad clan survived in al-Ushmunayn, near modern Mallawi, Minya Governate. The Banu Shadi, a subgroup of the Bali who served as emirs of Akhmim (in the modern Sohag governate) were also said to be Umayyad descendants. These groups endured the Fatimid period and were still present during the Mamluk sultanate.

There are also claims to Umayyad ancestry among rulers from the Sudan. It's sensible to take a cautious approach to these claims, since many genealogical traditions were assembled under the authority of servants of local kings who wished to connect themselves to the wider Islamicate and provide themselves with an ancestry that would legitimise them among their Muslim subjects.

Sultan 'Umara Dunqas of the Funj Sultanate hired a genealogist named al-Imam al-Samarqandi in the early 16th century CE whose work is likely the basis for all claims of Umayyad descent in the Sudan, and he was working for a king who felt endangered by the Ottoman Sultan Selim I and was trying to avoid an invasion. The genealogist may have been inspired by the story of 'Abdallah and 'Ubaydallah, reported by al-Mas'udi in the 10th century CE and repeated by al-Ashraf 'Umar and ibn Khaldun in the 13th and 14th centuries. According to these accounts, two sons of Marwan II named 'Abdallah and 'Ubaydallah escaped after their father was killed at Busir. They fled to Aswan and then kept going south, entering the lands of the Beja peoples. 'Ubaydallah died during the journey but 'Abdallah reached the Red Sea and crossed to Jeddah, where he managed to escape detection for a few years before being arrested and imprisoned for decades, only being released as a very old man. Despite the fact that 'Abdallah only travels through the Sudan on his way to the Hejaz, it may have been enough of a basis for the genealogy.

Sources

Harvey, L. P. (2005). Muslims in Spain, 1500 to 1614. University of Chicago Press.

Hasan, Y. F. (1965). The Umayyad genealogy of the Funj. Sudan Notes and Records, 46, 27-32.

Szombathy, Z. (2022). The Umayyads in Mediaeval Egypt and Claims of Umayyad Origin in the Sudan. Publications of the Office of the Hungarian Cultural Counsellor in Cairo 2020-2021, 81.