system
Given the following post, respond as if you're commenting on Reddit:
human
[Assassin's Creed] When did the Assassins actually start?

In the first Assassin's Creed, we find out towards the end that Al Mualim is just another Templar who was using his Assassin order to kill all of the other Templar leaders so he'd be the sole remaining leader of the organization.  Altair kills Al Mualim, and forms an independent Assassin order dedicated to actually opposing the Templars.

Is this the beginning of the Assassin/Templar split?  Or have their always been a semi-organized group of "assassins" opposing the Templars, perhaps under a different name?
gpt
The earliest history of the Assassin Order is murky at best.  There is currently no information on the founder of the Assassin Order, or indeed whether there was a single founder at all.  

What we do know is this:  The First Civilization and humankind fought a war in ancient times, but before the war could be resolved, the Earth was devastated by a solar flare.  This resulted in both civilizations nearly being wiped out.  Afterwards, humans and the First Civilization worked together to rebuild, and interbred during this period.  As a result, people who have First Civilization DNA in them can tap into their abilities, thus giving them a "sixth sense" that is commonly known as Eagle Sense.  These specially-endowed humans formed the basis for the Assassin Order.  

The earliest Assassin we can know of for certain was Darius, who killed Xerxes in 465 BC.  There is no way to confirm whether he was the first Assassin, but most likely he wasn't.  This indicates, of course, that the Assassin and Templar war far pre-dates Altair and Al-Mualim, who lived in the 12th century.