Catechu

Catechu ( /ˈkætɨʃuː/ or /ˈkætɨtʃuː/; also known as cachou, cutch, cashoo, Terra Japonica, khoyer or Japan earth) is an extract of any of several species of Acacia—but especially Acacia catechu—produced by boiling the wood in water and evaporating the resulting brew.