User blog comment:Master Sima Yi/Assassinews 03-03-'13 — Assassin's Creed IV: Black Flag trailer and screenshots/@comment-203.129.39.74-20130311135538/@comment-1379990-20130312154713

There had to be some organization because they were often trained in groups. Though ninjas were trained in spying, assassinating. They were like mercenaries, though you also had ninja clans. It wouldn't be impossible that one of these clans was of the Assassin order and that instead of spying and sabotage, they focused more on assassinating templars.