The history books that mention Cobra Kung Fu (Boli Yan She') say that it was lost many years ago.
Turns out that's not true at all!
Cobra was preserved by the Tong. The teachers of it began migrating to the US in 1900. They taught the young men in the Chinese communities because these communities had no police protection.
Eventually, these groups of protectors devolved into protection rackets. Such is the way with humans.