War of Fijar (Harb al-Fijar) or the Sacrilegious War
War of fijar was fought between Quraish and Kinana on one side and the Hawazin on the other. It lasted for sixteen years.
The given causes: The insult to a Hawazin maid by a Quraishite youth The boasts of a poet who struck by an indignant Hawazinite The insults hurled by a creditor on a Kinanite debtor
The real cause was that imperialist intrigues of Persian and Byzantium empire threatened Quraish’s commercial ambitions.
This war was soon followed by the League of Just, called the Hilf al-Fudhul.
For complete Islamic history notes click here.