[8] In the Crusader era it was known as Cassie, and in 1183 it was noted that Godfrey de Tor sold the land of the village to Joscelin III.

[9] In 1220 Jocelyn III's daughter Beatrix de Courtenay and her husband Otto von Botenlauben, Count of Henneberg, sold their land, including Cassie and the nearby Roeis (Khirbet Tell ‘er-Ruwesah/Tel Rosh), to the Teutonic Knights.

[11] Dayr al-Qassi was incorporated into the Ottoman Empire in 1517 and it belonged to the nahiya (subdistrict) of Jira, part of the Safad Sanjak (District of Safed).

The villagers paid a fixed tax-rated of 25% on a number of crops, including wheat and barley, as well as on goats and beehives; a total of 345 akçe.

[12][13] In the early 18th century, Dayr al-Qassi was a fortified village controlled by a local sheikh (chief) named Abd al-Khaliq Salih.

In 1740, Sheikh Zahir al-Umar, a local multazim (tax farmer) from the Banu Zaydan family whose strength was growing throughout the Galilee, struggled to gain control of Dayr al-Qassi.

[2] In 1881, Dayr al-Qassi was described in the PEF's Survey of Western Palestine (SWP) as being situated on a ridge, encircled by fig and olive trees and arable land.

[5] By June 1949, it was reported that the whole northern area had been "Judaised", including Tarshiha, Suhmata, Dayr al-Qassi, Tarbikha, Meirun, al-Sammu'i, Safsaf and al-Ras al-Ahmar.

[5] The Palestinian historian, Walid Khalidi, described the remaining structures on the village land in 1992: "A few stone houses still are used as residences or warehouses by the inhabitants of Elqosh.