Complex sentence: Their followup album was "The Sufferer & the Witness" in 2006, became a commercial success, peaking at number ten on the "Billboard" 200 as well as charting in several other countries.
Split into simpler sentences: Their followup album was "The Sufferer & the Witness" in 2006. It became a commercial success, peaking at number ten on the "Billboard" 200 as well as charting in several other countries.