Green’s Dictionary of Slang

bang n.4

also bhang
[Hind. भंग (bhaṅg), भँग (bhaṁg), Cannabis sativa; the term appears in Eng. in mid-16C but its use (through to mid-20C+) is simply as an exotic foreign word; by the 1930s, as bang, it was incorporated, slightly mis-spelt, into popular slang, a process that was accelerated by returnees from the ‘Hippie trail’ of the 1960s; bhang itself remains primarily a technical term, used to describe cannabis as produced and consumed in India and Pakistan]

[1930s+] cannabis, esp. in the form of hashish.

In derivatives

bhanged (adj.)

[mid-late 19C] (Anglo-Ind.) intoxicated by hashish.