Green’s Dictionary of Slang

(US drugs) hashish.

1944		O. Ferguson ‘Vocab. for Lakes, [etc.]’ AS XIX:2 104: The only term I think of which isn’t in general use is heesh for hashish.
1953		Anslinger & Tompkins Traffic In Narcotics 310: heesh. Hashish.
1960, 1975		Wentworth & Flexner DAS.