Like most anarchists, I am very interested in historic examples of anarchist, quasi-anarchist, or otherwise stateless communities and territories, including the usual examples like Catalonia, Ukraine, Shimnin, Strandzha, Iceland, Baja, Chiapas, Rojava, Slab City, etc. But a problem with these kinds of examples is that most of them were very limited in scale and lasted for relatively short, or very short, periods of time.
It is necessary to look for examples of societies and civilizations that were able to endure for centuries or even millennia while largely keeping the state under control and preventing external invasion and conquest. Ancient Greece appears to be the best model of such a civilization. Greece endured for centuries against a collection of thousands of cities with many different internal systems, with the cities fiercely safeguarding their independence, even when they occasionally clashed with each other.
The Holy Roman Empire, a collection of principalities and free cities that lasted for 1000 years between Charlemagne and Napoleon, is another example, along with the medieval leagues that existed during part of the same period.
Another issue involves the means through which some degree of autonomy can be achieved even within overarching state systems. The millet system that provided some autonomy to religious minorities in the Ottoman Empire is an interesting example.