With the 1921 Treaty of Ankara, Ras al-Ayn became a divided city when its northern part, today's Ceylanpınar, was ceded to Turkey.

[citation needed] Ras al-Ayn is located in the Upper Khabur basin in the northern Syrian region of Jazira.

The Khabur, largest tributary of the Euphrates, crosses the border from Turkey near the town of Tell Halaf, about 4 kilometres (2.5 mi) to the southwest of the city.

[12] So rather than the overground streams, it is the giant karstic springs of the Ras al-Ayn area that is considered the river's main perennial source.

The archaeological site is located on the southern edge of the mound Tell Fekheriye, around which today's Ras al-Ayn is built, just a few hundred meters south of the city center.

In later times, the town became known as "Rhesaina", "Ayn Warda", and "Theodosiopolis", the latter named after the Byzantine emperor Theodosius I who granted the settlement city rights.

[16] In the 19th century a colony of Muslim Chechen refugees fleeing the Russian conquest of the Caucasus were settled in the town by the Ottoman Empire.

"[19] After the fall of the Ottoman Empire and the 1921 Treaty of Ankara, Ras al-Ayn became a divided city when its northern neighborhoods, today's Ceylanpınar, were ceded to Turkey.

During the following eight months, the Kurdish-majority People's Protection Units (YPG), present from the outset, gradually entrenched its position, and eventually formed an alliance with a non-jihadist FSA faction.

[20][4] After 11 days of clashes and siege, the Syrian Democratic Forces and the Kurdish YPG retreated from Ras al-Ayn as part of a ceasefire agreement.

[21] On December 10, 2020, a car bomb exploded at a checkpoint run by Turkish-supported Syrian National Army rebels in Ras al-Ayn.

[23][22][24] Turkish authorities blamed the Peoples Protection Units (YPG) for the car bombing as Turkey claims they are affiliated with the Kurdistan Workers Party (PKK).

[31] War crimes committed since the Turkish occupation began have since caused an exodus of Kurds, Christians, and other minorities from the town such as Assyrians and Armenians.

[32] The Turkish government's resettling of mainly Arab and Turkmen Syrian refugees from other parts of Syria in Ras al-Ayn has further altered the town's demographics.