User blog comment:Master Sima Yi/Assassinews 03-12-'14 — New Assassin's Creed in Victorian London leaked/@comment-83.216.192.151-20141216165909/@comment-24849873-20141217101409

Its complicated, through different times different branches were wearing different clothes but in the middle ages throughout the Levant and possibly Europe the robes were formely white, but during the Russian revolution they all were wearing white too as well as Arbaaz Mir so maybe Indian assassins during the British Raj aswell.

American colonial assassins could wear what ever they wanted, sometimes not even a hood but many still were wearing white like Duncan and Achillies. I think Chineese assassins mainly wear black (we might know more when China Chronicals is released.

I think it slowly got lost because templars would generally suspect a person in white more often.