There was a time, not really all that long ago, in the scheme of things, when the anarchs and the Sabbat seemed tailor-made for each other. The anarchs espoused freedom from the oppression of the Camarilla elders, and the Sabbat offered just such an escape in the form of the bond-breaking Vaulderie. Both sects were far more openly violent than the Camarilla, and both seemed willing to acknowledge their inhuman natures.
Then the anarchs got a really good look at what the Sabbat is.
They don't offer freedom at all, just a new form of enslavement. The Vaulderie might allow a bit more room to roam than the blood bond, but ultimately, it's still just another leash. Forced devotion to a fanatic ideal isn't any better than bondage to an ancient monster, not when that fanatic ideal seems to be nothing less than the glorification of the worst parts of Kindred nature. The don't just "acknowledge" their inhumanity, they venerate it, treating mortals like less than chattel. Sure, even the Camarilla Kindred refer to the mortals as kine, but at least the don't make a practice of glorifying mass murder. How could the anarchs justify claiming equality with Kindred more powerful than they, if they treated their inferrors - even mortals - in ways they'd never accept from their own elders?
To say nothing of the Sabbat's holy war against the Antediluvians. Hello? Why not go to war against the dinosaurs while you're at it? Oh, wait, that's right. They're extinct! Holy shit!
Tonight, the vast majority of the anarchs bitterly oppose the Sabbat and everything they stand for. As mentioned above, they've come to realize that the Camarilla, for all its flaws, is home, and its a home that requires defending. The Sabbat is no longer to be envied or emulated as once it was. The Sabbat is the enemy.
Unfortunately, the minority of anarchs who haven't yet figured this out, or else refuse to acknowledge it, is still a sizable one. To some, the call of the Sword of Caine is too strong to be ignored. A sect where your elders can never blood bond you, where you don't have to follow any damn Traditions or kowtow to the mortals beneath some follish Masquerade, where every Cainite has a purpose to unlife....It's all quite attractive to many of the aimless neonates who find their way into the ranks of the anarchs. Some only dream about it, talk about it, but never actually take that final step. A small but steady flow of anarchs does indeed join the Sabbat, though. In fact, the anarchs are still a major source of new recruits for the Black Hand, though fewer now than in nights past.
This isn't to say that the Anarch Movement doesn't have some nonviolent contact with the Sabbat. A small anarch population exists in quite a few Sabbat cities. They do tend to keep their heads down much of the time, since they'd rather not draw attention. Some actively work against the Black Hand, trying to sabotage the Sabbat from within their own territory. Most, however, are far less brave (or foolhardy..) and dwell in Sabbat domains primarily because they have nowhere else to go.
Unlife is unpleasant at best for most of these anarchs. The Camarilla can be aggravating with its "You're part of us whether you want to be or not" policy, but it's vastly preferable to the Sabbat's "If you aren't with us 100 percent, you're an enemy and we're going to rip you to pieces and eat your soul" outlook. Anarchs dwelling in and around Sabbat cities learn quickly to to remain inconspicuous and to mimic enough of the basic Sabbat attitudes and rituals so they can pass if questioned casually.
Some nomadic anarch coteries enjoy a more active relationship with the bloody-minded sect. The Sword of Caine is always happy to receive information or favors from vampires with access to Camarilla domains, and the anarchs themselves are thrilled to receive Sabbat support when waging a covert war against a particularly loathsome Camarilla elder. Anarch coteries and Sabbat packs work suprisingly well together in those circumstances where they share a mutual goal. Such instances are proving more and more infrequent, in light of both the recent war and the anarchs' new interest in choosing their targets more carefully, but it still happens frequently enough that anarch and Sabbat Kindred don't necessarily attack one another on sight. It's also frequent enough that the Camarilla elders remain convinced that the Sabbat and the anarchs maintain a far closer relationship than is actually the case, a misonception that only perpetuates the cycle of hatred and fear between elders and anarchs.
~Guide to the Anarchs, White Wolf Publications 2002