Conversation so far:
What was the federation of northern syria?
With the Syrian Civil War, the Kurdish populated area in Northern Syria has gained de facto autonomy as the Federation of Northern Syria - Rojava
when did the Kurdish populated area in Northern Syria gain de facto autonomy as the Federation of Northern Syria - Rojava occur?
This led to the establishment of the Democratic Federation of Northern Syria (DFNS) in 2016, which was renamed the Autonomous Administration of North and East Syria (NES) in 2018.

Question: how did they gain the autonomy?
Self-contained rewrite: how did the Kurdish Democratic Union Party (PYD) gain the autonomy in Northern Syria?