Thomas was born in Vienna, Austria. He took up drumming at age five. In addition to lessons at local music schools and years of private tuition, he was classically trained at the Vienna Conservatory of Music. After leaving the conservatory in 1985, Lang began working professionally, working his way through the European pop, rock and jazz scenes. As a session musician he played for artists such as John Wetton, Robert Fripp, Glenn Hughes, Peter Gabriel, Asia, Nik Kershaw, Tina Turner, Robbie Williams, Kelly Clarkson, Sugababes, Geri Halliwell, Emma Bunton,
Victoria Beckham, Ronan Keating, Steve Hackett, 911, Boyzone, Falco, Nina Hagen, Steve Jones, Mick Jones, the Commodores, George Michael, Doogie White, B*Witched, Gianna Nannini, Lighthouse Family, Westlife, Kylie Minogue, the Blockheads, Sertab Erener, Vienna Art Orchestra, Bonnie Tyler, Nadine Beiler, and Paul Gilbert. In 1995 Lang released his debut solo project, Mediator, which topped the charts in Europe and garnered positive reviews.