Yass (jass) is a Polish music style from late 1980 that mixes jazz, improvised music, techno, punk rock, and folk. This style began in Gdańsk and Bydgoszcz. The term was coined by Tymon Tymański, a double-bass and guitar player from Gdansk, who wanted to stress a novelty of the new style.
Yass is a term coined at the beginning of 1990s by Polish Avant-Garde Jazz musicians Tymon Tymański, Mazzoll and Tomasz Gwinciński who wanted to stress a novelty of the new style, to describe the cross-genre, frequently arrhythmic, improvised music they played with e.g. Miłość, Łoskot and Mazzoll & Arhythmic Perfection. Yass comprises the stylistics and elements of genres ranging from Folk to Punk Rock.
The Yass scene emerged in Tricity (an aggregate of the three neighbouring towns of Gdańsk, Gdynia and Sopot) and Bydgoszcz whose Mózg became the “home venue” for Yass performers (e.g. Koncert w Mózgu) with its own label releasing a number of Yass productions.
A good overview of the Yass scene comes with the compilation album Cały ten Yass! released by Jazz Forum magazine just after the genre’s heyday.