Kurds are the largest ethnic minority in Syria. There are large numbers of Kurdish people also in Turkey, Iraq and Iran, but they don't have sovereign country.
this is a significant part of the answer. The Versailles treaty after the 1st World War was
supposedly designed to stop precisely this problem from happening, but oops, they accidentally designed the treaty in a way that specifically kept the Kurdish problem stored up until a future date. It was not possible to redraw the map in such a way that all these intermingled ethnic groups could be completely segregated, but in the case of the Kurds, it would have been incredibly easy to recognise at least some kind of Kurdish sovereign territory, they likely chose not to in order to exploit the situation in future.
These were very smart people, (Churchill, Clemeceau, Wilson supposedly less so) they would have been aware of all this at the time. The significance of controlling the crude oil market was long since well known, and the Kurdish region was likely chosen as a geo-strategic pivot to keep the Middle East in the right amount of turmoil to let the gangsters continuously assert their authority; keep puppets in charge of regional powers, and use them to control the price of oil and to assure which currency oil is priced in.
My question is, why Turkey decided to make this "buffer zone" on the Turkey-Syria border and attacked the Kurds who have many sympathisers around the world. I think many people will start to boycott Turkey because clearly they are the aggressor in this conflict. This is the beginning of a civil war which could transform into a World War 3 if the US and Russia get involved. WW3 is not very likely as no-one can really afford it at the moment. However even in best case scenario, the Turkey-Kurds conflict will result in deaths of many civilians and even more refugees will flew to Europe which already can't cope with all of them coming from Syria and Africa.
The Turkish establishment (particularly those connected to oil and the military in Turkey) are
probably orchestrating this whole sequence of events in concert with similarly powerful figures in the US
and Russia. It's important to remember that as much as the big powers may attack each other publicly from time to time, their real enemy is the population of the
countries fiefdoms they control. The US, Russia, Turkey, China, Japan, Brazil, the EU.... likely the majority of their public disagreements have more to do with using the tension to elicit tribal instincts in regular people than they have to do with any real disagreement. These so-called enemies have more in common with one another than they do with the serfs whose interests they pretend to represent.