I posted once before on Ireland and their anarchy that lasted for more than a thousand years:

This most remarkable historical example of a society of libertarian law and courts first came to my attention while reading Murray Rothbard’s For a New Liberty. This was a society where not only the courts and the law were largely libertarian, but they were basically anarcho-capitalist in the modern sense of the phrase. This Celtic society was not some primitive society or tribe but rather it was a highly complex society. Ireland for centuries was the most advanced, most scholarly, and most civilized society in all of Western Europe. And all without a government!

Murray Rothbard documented the Irish Anarchy in his book « For a New Liberty: The Libertarian Manifesto«  were he wrote in part:

The most remarkable historical example of a society of libertarian law and courts, however, has been…