In the 11th century , large numbers of pastoralists , known as Hilalians , fled Upper Egypt .
In the 11th century , large numbers of pastoralists , known as Hilalians , moved westward into Libya and as far as Tunis .
In the 11th century , large numbers of pastoralists , known as Hilalians , fled Upper Egypt and moved westward into Libya and as far as Tunis .