For over 100 years, the Kurds have been settled in parts of what is Turkey, Syria, Iraq, and Iran.
The main part of Syria that was theirs is the northeast part that sticks out like a horn. They've had a guerilla army there for decades.
But ISIS came along, and they were strong along the Euphrates river up to the border with Turkey. This has historically been an Arab (not Kurd) area.
The Russians cooperated with the Syrian government army to take ISIS territory up to the west side of the Euphrates.
The Turks took a little bit of ISIS territory near where the river meets their border.
And we cooperated with the Kurds to take ISIS territory up to the east side of the Euphrates.
So the Kurdish armies today control a lot of land that never used to be theirs, closer to the river.
Now Turkey is saying they just want to claim a strip of territory along the entire Syria-Turkey border and resettle Syrian Arab refugees that are currently in Turkey there.
That sucks for the Kurds, but, so long as Turkey stops where they say they're going to stop, the Kurds will still control more of Syria than they did before the conflict started.
Time will tell if this is a simple migration/land swap or a genocide.

---