Titus Livius (Livy), The History of Rome, Book 38
Evan T. Sage, Ph.D., Ed.

19. Later the ambassadors from the people of Oroanda brought surer news, that the tribe of the Tolostobogii had occupied the Olympus range; that the Tectosagi, separated from them, had made for another mountain which was called Magaba; [2] that the Trocmi had left their wives and children among [p. 67]the Tectosagi and with their armed forces on the¹ march had decided to aid the Tolostobogii. [3] The chiefs of these three tribes at this time were Ortiago and Combolomarus and Gaulotus. They had adopted this plan particularly for conducting the war —that, when they had occupied the highest peaks in the region, conveying everything there which would be sufficient for their use over however long a period, they would wear down the enemy by exhaustion; [4] for, they were convinced, the Romans would neither venture to climb over such steep and difficult ground, and, if they did attempt it, they could be stopped even by a small force or pushed back, nor would they sit quietly at the foot of cold mountains and endure chill and hunger. [5] And, although the very height of the place was a defence, they also threw a ditch and other fortifications around the summits which they had occupied. [6] They took little forethought for a supply of missile weapons, because they believed that the very roughness of the terrain would furnish stones in abundance.