Bosnia before the Turkish Conquest

"Bosnia before the Turkish Conquest" written by William Miller and first published in 1898 is a brief history of this Balkan country from the earliest time to the end of the Middle Ages.
"But the old Illyrian inhabitants had to acknowledge the superiority of another race. About 380 B.C. the Celts invaded the peninsula, and, by dint of continual pushing, ousted the natives of what is now Servia, and so became neighbours of the Ardiaei. Their next step was to drive the latter southward into the modern Herzegovina, and to seize their possessions in North Bosnia. Instead of uniting against the Celtic invaders the Illyrian tribes fell to quarrelling among themselves over some salt springs, which were unfortunately situated at the spot where their confines met. This fratricidal struggle had the effect of so weakening both parties that they fell an easy prey to the common foe. The victorious Celts pursued their southward course, and by 335 B.C. both Bosnia and Herzegovina were in their power, and the Illyrians either exiles or else subject to the Celtic sway. This is the first instance of that fatal tendency to disunion which has throughout been the curse of these beautiful lands. The worst foes of Bosnia and the Herzegovina have been those of their own household."--William Miller, 1898