User blog comment:Jpx400/Assassin's Creed IV Settings/@comment-4868246-20120915175723

Back to the Middle East!!

• Patriotic goosebumps*

Or ancient Greece, Despite the fact that the Assassin Order was established in the 11th century, Ubisoft could break some boundaries and go further back and still stay true to the principles of AC. Altair states in his Codex, "You cannot kill a creed. Even if you kill all of its adherents, destroy all of its writings – these are a reprieve at best. Some one, some day, will rediscover it. Reinvent it. I believe that even we, the Assassins, have simply re-discovered an Order that predates the Old Man himself... "

We can infere that there is a possibilty that the Assassin Order existed prior to the recorded establishment (1091) or the "reinventiontion" as Altair portrayed it.

Ps. "The Old Man" is a reference to Rashid ad-Din Sinan (commonly known as "Al Mualim"), the leader of the Masyaf branch of the Assassin Order :)