LEGO Trains is one of the longer running themes that dates back from 1966 and ran up until 2006. During its run there were multiple sets released running on various power platforms from 4.5volt, to 9 and 12 volt sets. Later in 2011 LEGO released additional train sets using RC and Power Functions controllers under different themes like City.
2006 LEGO Sets
2006 for LEGO was a year of new themes being introduced and a number of well known themes being retired. LEGO in 2006 introduced and discontinued The Avatar: The Last Airbender, introduced the original Batman theme, Exo-Force, Mindstorms NXT, SpongeBob SquarePants, Remote control Trains and Aqua Raiders. However, the following themes were discontinued; Clikits, Vikings. While LEGO Sports was re-introduced in 2006 with a couple Soccer/Football sets.