The history of the ukulele began on the Portuguese island of Madeira. When Madeiran workers emigrated to the Hawaiian islands in the late 19th century, they brought with them the machête, a small guitar-like instrument. The local population were enchanted by the D-G-B-D-tuned machête, and immigrant luthiers began producing a G-C-E-A-tuned version in Hawaiian koa.
The ukulele was born, and koa is still loved for its warm, clear mid tones and dark grain. By contrast, mahogany produces crisp high-mids, spruce is well-rounded, and maple is transparent, with few overtones. Modern ukes can even come in a 'bass' format, pushing booming low registers from their wafer-thin bodies!