My sources:
M. Gast 1972: "Témoignages nouveaux sur Tin Hinan, ancêtre légendaire des Touareg Ahaggar", Revue de l'Occident musulman et de la Méditerranée, vol. 9, pp. 395-400
Unesco general History of Africa Vol II, ch. 20 
quotation Unesco general History of Africa, vol. III, p.125
"Excavations in Abalessa brought to light a large quantity ot objects suggesting the existence of an old route between the southern Morocco and the Hoggar "from the fourth century of the Christian era" ät "a time when camels were in use".