Khirbat al-Tannur, also Allar al-Sifla (Lower Allar), was a Palestinian Arab hamlet in the Jerusalem Subdistrict, near Allar. It was depopulated during the Nakba in 1948 on October 21, 1948 under Operation Ha-Har. It was located 18.5 km west of Jerusalem.
In the 12th century, during the Crusader era, a rural monastery was established consisting of several barrel-vaulted buildings, an enclosure wall and a chapel. British archaeologist Denys Pringle proposed that the complex was a known Cistercian house called "Saluatio" established in 1169.
In the 13th century it was recorded in two documents that income from the village supported the Madrasa al-Mu'azzamiyya, north of the Haram al-Sharif in Jerusalem.
In 1596, the village appeared in Ottoman tax registers as Allar as-Sufla in the Nahiya of Quds in the Liwa of Quds (Jerusalem). It had a population of 7 Muslim households and paid taxes on wheat, barley, summer crops and olives.A visitor in 1875 wrote that it had a population of 400, but soon afterwards it was apparently abandoned until the 20th century. In the late Mandate period it was classified as a hamlet.
Six Arab families from Bayt 'Itab who settled amid the Crusader ruins were involved in a long-standing feud with Allar villagers over water use, land ownership and grazing routes, which only ended in 1948 when both places were depopulated.
When the site was inspected in 1993, there were ten houses of which six had been destroyed.