Convoys carrying civilians and family members of Islamic State fighters left the last area held by the extremist group in eastern Syria on Wednesday.
Around 30 trucks, mostly carrying women and children, left Baghuz village and headed towards a temporary camp north-west of it.
Some extremist militants, who have surrendered, were also evacuated.
“We will be back,” a man believed to be an Islamic State fighter was heard shouting from the truck as it arrived at a checkpoint manned by the Kurdish-led, US-backed Syrian Democratic Forces (SDF).
Children looked weary, pale and covered with dust.
The SDF forces started an offensive to expel Islamic State from Baghuz, the only area still under its control in the eastern province of Deir al-Zour, earlier this month.
This week, SDF spokesman Mustapha Bali estimated there were still around 500 Islamic State fighters inside Baghuz.
On Tuesday, dozens of trucks were seen heading to al-Basteen area, the area inside Baghuz village where Islamic State members have been holed up for several days.
After reaching the temporary camp, women and children are expected to be transferred to al-Hol camp, in north-eastern Syria, which is controlled by the Kurds.
Men will be interrogated by the SDF.
On Tuesday, UN High Commissioner for Human Rights Michelle Bachelet had expressed concern about the situation of some 200 families, including many women and children, who were reportedly trapped in the tiny area still under the control of Islamic State.
“Civilians continue to be used as pawns by the various parties,” Bachelet said.
“I call on them to provide safe passage to those who wish to flee, while those wish to remain must also be protected as much as possible,” Bachelet added.
Baghuz is in the eastern Deir al-Zour province, bordering Iraq. The SDF, which has led the fight against Islamic State in northern and eastern Syria, began its campaign in Deir al-Zour province in September.