Green’s Dictionary of Slang

1. (drugs) opium.

1893		Herald (Los Angeles) 3 Sept. 11/2: The vistors [...] explained they wanted to smoke. ‘Bing goye ship goe san ah pin yen,’ muttered the Chinaman.
1897		Courier (Lincoln, NE) 7 Aug. 12/4: Her smile was like ka-pen-yen-see, the Black Smoke, which makes one drunk and dream of heaven.
1906		Tulsa Dly World (OK) 12 Oct. 2/1: No Longer Will the Heathen Chink be Permitted to Enjoy the Seductive ‘Pin Yen’.
1915		G. Bronson-Howard God’s Man 250: He winked so prodigiously this time that Arnold was quite sure this particular ginseng was a euphemism for the forbidden pen-yen.
1919		Bridgeport Times (CT) 3 Apr. 16/3: Not only the Pin yen (commercial opium) was found in the Hop Toys but Yen Shee (ashes), evidence that smoking had been in progress.
1922		E. Murphy Black Candle 113: Opium ready for smoking is usually about the consistency of black molasses, or of tar. Pedlars call it ‘mud’ but the Chinese name for the mixture is pen yang.
1931		Irwin Amer. Tramp and Und. Sl. 143: Pen Yen.–Opium.
1941		V. Davis Phenomena in Crime 92: There are three grades of opium. Pin Yen is the finest.
1953		Anslinger & Tompkins Traffic In Narcotics 313: pen yen [...] pinyon. Opium.
1962		Ragen & Finston World’s Toughest Prison 812: pen yen – Opium.
1971		E.E. Landy Underground Dict. (1972) 147: pen yuen [...] Opium.
2001		ONDCP Street Terms 16: Pen yan — Opium. [Ibid.] 17: Pin yen — Opium.
2004		(ref. to 1885) Wave Mag. 🌐 They mounted an 1885 study [...] and found 26 opium ‘resorts’ with a total of 320 bunks. Every resort was given a rating that ranged from ‘filthy’ to ‘very filthy’ with additional notes if the opium, or ‘ah-pen-yen,’ was cooked up at the same den it was smoked.

2. (US drugs) second-rate opium.

1908

Eve, Star (Wash., DC) 1 Sept. 2/5: Raw opium of an infeior grade called by Chinamen ‘pen yen,’ [...] about 70 per cent opium and 30 per cent yen seed.