Sudanese Arabs today are practically geneticall identical to Christian ear Nubians meaning that this Gigantic migration of Arabs that completely changed the genetics of people in the region didn't actually happen.
Also I am talking about autosomal DNA. You can have massive changes in y-dna and mtdna without a much change in autosomal DNA.
The nation of chad has majority haplogtoup r1b like western Europeans
Pre Islamic Nubians from 9th century CE admixture dates back to 2-3rd BCE:
Using 815 CE as the midpoint of the calibrated modeled age range for Kulubnarti, this
places admixture occurring on average during the early-2nd to late-3rd centuries CE(95%CI), although the dates obtained with this method are based on a model of a single pulse of admixture and thus reflect an intermediate value if the true history includes multiple waves or continuous admixture, which is likely at Kulubnarti given the individual-level variance in ancestry proportions.
How can Sudanese Arab be identical to Christian Nubians when they have additional 40 % Arab admixture?
Modern Sudanese Arabs:
Target: Sudanese_Arab_Batahin
Distance: 0.7569% / 0.00756915
43.4 Nubia_Medieval_Christian_Era_Kulubnarti
40.4 Yemeni_Mahra
12.6 Dinka
3.6 Kenya_Pastoral
Modern Nubian:
Target: Nubian_Halfawi
Distance: 1.5416% / 0.01541644
78.4 Nubia_Medieval_Christian_Era_Kulubnarti
15.0 Yemeni_Mahra
6.6 Dinka