Following the Greco-Turkish War of 1919–1922, the present course of the border was established in 1923 by the Treaty of Lausanne, which also left the so-called "Karaağaç Triangle" (Greek: Τρίγωνο του Καραγάτς), a suburb of the city of Edirne, Turkey, as a Turkish exclave on the western side of the river.

[6] As of June 2015[update], 124,000 migrants had arrived into Greece, a 750 percent increase from 2014, mainly refugees stemming from the wars in Syria, Iraq, and Afghanistan.

[8] In September 2015, the photos of dead 3-year-old Alan Kurdi, who drowned when he and his family were in a small inflatable boat which capsized shortly after leaving Bodrum trying to reach the Greek island of Kos, made headlines around the world.

Konstantinos Vardakis, the top EU diplomat in Baghdad, told The New York Times that at least 250 Iraqis per day had been landing on Greek islands between mid-August and early September 2015.

At Athens, officials voiced worries that Turkish monitors overseeing the deal in Greece had been abruptly pulled out after the failed coup with little sign of them being replaced.

[14][15] As migrants tried to breach the border fence using tools, they also set fires, threw stones, and Molotov cocktail firebombs over to the Greek side and there are videos of Turkish security forces in uniform and plain-clothes, firing tear gas at Greek forces and a Turkish armored vehicle attempting to pull down the border fence by tugging on an attached cable.

[17] On 2 March, Muhammad al-Arab, a Syrian asylum seeker was shot dead on Turkish soil from 15–135 metres (49–443 ft) away.

Forensic Architecture reviewed the evidence and found that one Pakistani, Muhammad Gulzar, was killed and seven were wounded, and determined that it was "highly probable" that the live rounds came from the Greek side of the border.