Ja'far ibn Fallah or ibn Falah was a Berber general of the Kutama tribe in the service of the Fatimid Caliphate. He led the first Fatimid attempt to conquer Syria in 970–971, but his attack on Byzantine-held Antioch was repulsed, and he lost his life in June 971 fighting against the Qarmatians.
In summer 969, the troops of the Fatimids of Ifriqiya, under the command of Jawhar al-Siqilli, conquered Egypt from its Ikhshidid rulers. The only resistance was offered by the regiments of the Ikhshidid army barricaded on the island of Rawdah Island near the capital of Fustat, but the Nile was low and the Fatimids' Kutama troops quickly crossed it and massacred the Ikhshidid troops. At the same time, further north, the Byzantine Empire seized Antioch. Seized with the spirit of jihad and aiming to legitimize their rule, the Fatimids used the Byzantine advance on Antioch and the "infidel" threat as a major item in their propaganda aimed towards the newly conquered region, along with promises to restore just government.
Jawhar therefore sent Ja'far ibn Fallah, who had distinguished himself before Fustat, to invade Palestine, where the remnants of the Ikhshidids were holding out. Ibn Fallah defeated and captured the Ikhshidid governor al-Hasan ibn Ubayd Allah ibn Tughj and took Ramla on 24 May 970. He then moved against Tiberias, held by the ghulam Fatik and his Banu Uqayl Bedouin allies. Fatik was killed through treachery, while Ibn Fallah used other Bedouin, the Banu Murra and the Banu Fazara, to drive the Uqayl north towards Homs. At the news of these events, the Ikhshidid-appointed governor of Damascus, Shamul, surrendered himself to the Fatimids. The Damascenes however resolved to resist and set up a governor of their own under the Abbasid Ibn Abi Ya'la and a certain Muhammad ibn Asuda, after Ibn Fallah's Kutama soldiers mistreated and robbed a delegation of leading citizens. The Damascene militia drove off the first detachments of the Fatimid army that appeared before the city walls, but as soon as Ibn Fallah himself with the bulk of his force appeared before the city in November and they were driven back behind the city walls, they offered to surrender. In stark contrast to Jawhar's leniency to Fustat, Ibn Fallah imposed humiliating terms on Damascus, demanding that the women come out and let their hair down in the dust. During the takeover of the city, the Kutama pillaged the markets and clashed with the populace for three days, after which Ibn Fallah executed several prominent citizens. This quietened the situation for the time, and Ibn Fallah secured Damascus by erecting a citadel in the city, but it left a legacy of hatred towards the Fatimids and their Berber troops in the city.