Topic summary
YPG

Extracted from the Wikipedia article People's Defense Units.
Late 2012: Islamist attacks make YPG dominant
While many rebel groups clashed with the YPG, jihadist and Salafist groups did so the most often. The YPG proved to be the only Kurdish militia able to effectively resist the fundamentalists. While the YPG protected the Kurdish communities it was able to extract a price: it prevented the emergence of new, rival militias and forced existing ones to cooperate with or join the YPG forces on its terms. This was how the Islamist attacks enabled the YPG to unite the Syrian Kurds under its banner and caused it to become the de facto army of the Syrian Kurds.