The Fijar Wars (Arabic: حرب الفِجَار, romanized: Ḥarb al-Fijār, lit. 'the Sacrilegious Wars') were a series of battles that took place in the late 6th century mainly between two major tribal confederations of Arabia, the Quraysh and the Hawazin. According to the sources, the fighting took place on eight days over the course of four years.

The conflict takes its name from the fact that its battles took place during the sacred months during which warfare was prohibited—a prohibition that usually enabled commerce to take place without interference from tribal feuds.^{[citation needed]}

The war was between 'two great confederations including townsfolk of Mecca and Taif': on the one hand, the Qays (excluding the Ghatafan) and, on the other, the Quraysh and the Kinana. Various Qaysi tribes participated, included the Hawazin, Banu Thaqif, Banu Amir and Banu Sulaym.

The Lakhmid king of al-Hirah, al-Nu'man III commissioned a leader of the Banu Amir, Urwa al-Rahhal, to lead the king's caravan to the annual market at Ukaz in the Hejaz. Al-Barrad ibn Qays, a member of the Kinana who had been expelled from his tribe, had requested the commission, but Urwa, who frequented the king's court, mocked al-Barrad for being an outlaw and persuaded al-Nu'man to appoint him instead. As he led the caravan to Ukaz, Urwa was ambushed and slain by al-Barrad, who proceeded to seize the caravan's goods. Al-Barrad's attack occurred during the sacred months when fighting was forbidden among the Arabs.

In response, Abu Bara, the preeminent chief of the Banu Amir and its parent tribe, the Hawazin, called his tribesmen to arms. A leader of the Quraysh, Harb ibn Umayya, was allied to al-Barrad, but the Quraysh also had close relations with the Kilab, the branch of the Banu Amir to which Urwa and Abu Bara belonged. The Kilab and the Ka'b, another branch of the Banu Amir, belonged to the Ḥums, a socio-economic and religious pact including the Quraysh and other tribes living in the Ḥaram (the area around Mecca considered inviolable by the Arabs). The Kilab and the Ka'b did not live within the Ḥaram. They owed their membership to their maternal Qurayshite descent.

The attack precipitated a conflict which lasted four years. The first three days of fighting (sometimes considered one war, sometimes three) consisted of brawls.

News of the killing reached Ukaz, where al-Barrad's patron, Harb ibn Umayya, had gathered with other chieftains belonging to the Quraysh. Realising that the Banu Amir would be seeking revenge for the killing of Urwa, the Quraysh and Kinana set off for Mecca. The Taymite chieftain Abd Allah ibn Jud'an reportedly supplied armor to one hundred men of the Quraysh. They were pursued by the Hawazin, who attacked them at Nakhla; the day of the battle is accordingly known as yawm Nakhla ('the day of Nakhla'), and is usually counted as the fourth day of fighting in the ḥarb al-fijār and the first day of the second war (though it is sometimes counted as the fourth day of the first war).

As night fell on the yawm Nakhla, the Quraysh and Kinana managed to escape to the Ḥaram. At that point, the Kilab halted their pursuit in fear of violating the sanctity of the Ḥaram. Abu Bara's and the Kilab's participation in the war was restricted to the day of Nakhla.