Pathrusim ben Mizraim

Biography
Pathrusim, per the Book of Genesis 10:13-14, is the son of Mizraim, the grandson of  Ham and a great-grandson of  Noah who fathered the many Mizraim tribes that settled in the land of Egypt.

Pathrusim were a people descended from Mizraim, according to Genesis 10:13, 1 Chronicles 1:11, who who inhabited Pathros (i.e., Upper Egypt).

Book of Jasher Narrative
In Parry, J. H. (ed.). [http://www.sacred-texts.com/chr/apo/jasher/10.htm 10:23. Book of Jasher], the Pathrusim and Casluhim intermarried resulting in the Pelishtim, Azathim, Gerarim, Githim, and Ekronim.

"23 And the children of Pathros and Casloch intermarried together, and from them went forth the Pelishtim, the Azathim, and the Gerarim, the Githim and the Ekronim, in all five families; these also built themselves cities, and they called their cities after the names of their fathers unto this day."