Turkey and genocidal ethnonationalism go way back

Institutional racism against Kurds has been a problem in Turkey for ages, Erdogan has extended it into military campaigns in the north of Iraq ever since the US bombed it into state collapse, and has repeated that in northern Syria ever since the civil war started. This has always been accompanied by repression against Kurdish political organizations in NATO ally states, it was one of Turkey's conditions for letting Sweden and Finland join NATO. This leads to all kinds of weird, contradictory situations, like the German government at the same time arming the YPG and making public support of it completely illegal.

I had some reactionary Turks in my family by marriage for a while and I asked decades ago when I was in Turkey why they were against the Kurds having their own deal/more autonomy etc and the answer was, resoundingly, that to surrender the territory or control of it would "weaken" Turkey. they saw the entire Kurdistan movement as a "western plot" to "divide and conquer" the Turks.

of course, these were the sort of people who liked the US military being huge because it meant our country was strong and that's why Turkey allied with the US, was because the US has strength and that's all that matters. so, like nakedly fash.

From the discussions I've had, they see it as their land that the Kurds are trying to take from them. Of course, Turkish pan-nationalism even claims the Baltics and western China as their native land so take that with a grain of salt. Claims that Kurds are uneducated, religious fundamentalists with large families they can't provide for and will ruin* and overrun the country with their customs, etc.

As others said, racism and fascism. Typical Turkish nationalism.

What is specifically in question in Syria is the Kurdish areas of Syria became self-governing through the civil war, and the Turks claim they have ties to the armed Kurdish organizations that exist in Turkiye. Realpolitik they're just grabbing territory and resources, dams, oil, etc. but its justified through the lense of protecting Turkiye from the PKK who are supposedly supported by the Kurds in Syria and Iraq

i mean they do support the PKK to some extent, who knows if they can afford to arm/supply them or anything. but the conflict between the PKK and the Turkish government springs from the decades-long attempted ethnic cleansing of the Kurdish minority in Turkiye, the PKK were justified.

residual anti-communism and/or turkey has kurds, who also want kurdistan

Kurds have been an ethic underclass in Turkey since the founding of modern Turkey, where Atatürk, for unknown reasons, decided to take a hard-line stance against them. Obviously the ethnic conflict dates back further than that but this traces a direct through line to today.

Then it's basically the same old deal - they got treated like second class citixens, they faced all sorts of government repression and pogroms etc. such that the likelihood of modern Turkey reaching an accord with the Kurds is either a pipedream or its going to take like a century+ of both sides working diligently and in good faith to resolve this conflict.

You know how Romani people are treated as essentially subhumans in Europe, how they are excluded and ostracised and subject to all sorts of repression as well as frequent attempts to displace or exterminate them (at least historically speaking)? Yeah, that's a pretty good match for how Kurds are treated especially in Turkey.

The Kurds in NE Syria are led by the PKK, which is the mortal enemy of Turkey. The PKK leader, Abdullah Öcalan, has been imprisoned on Turkey's own Alcatraz alone for years and years now. The PKK has worked closely with Palestinian liberation movements, especially the PFLP, with training, coordination and mutual support going back decades. The PKK was ML until fairly recently where Öcalan took a sorta libertarian turn, being directly inspired by Murray Bookchin's (kinda) post anarchist Libertarian Municipalism which Öcalan developed into Democratic Confederalism, which the PKK has been attempting to implement in Rojava.

The chances of Rojava surviving intact after the recent turn of events in Syria are slim. Turkey will do whatever it takes to steamroll Rojava imo and if they aren't doing it right now then the only reason is that they're probably drawing up their plans for how to go aboit it. Israel has conducted precision strikes to deal a major blow to Rojava/the SDF's military capacity.

Of all the groups in the Syrian civil war, the SDF is really the only one qualified for the term "moderate rebels" imo, they are secular and progressive and, although I have significant criticisms of Rojava and I think they are glamourised by anarchists undeservedly, in a situation where Assad has been taken off the board they are by far the best option and, being led by the PKK, Rojava is the only shot at something radical left emerging from the Syrian civil war although how hopeful one is about those prospects-not to mention the prospects of Rojava surviving in this new phase of the Syrian civil war-are very much debatable.