The two Tocharian languages, Tocharian A and Tocharian B, are closely related and clearly form a branch within Indo-European. Therefore, the discussion of the evidence for the Tocharian branch focuses on the most important changes that have shaped and typologically changed the language. Many innovations of Tocharian, especially in the lexicon, are due to language contact. Some of these contacts took place before the break-up of Proto-Tocharian, while others took place at later stages. It is widely held that, after Anatolian, Tocharian was the second branch to split off the Indo-European proto-language, which may be termed the “Indo-Tocharian” hypothesis. A selection of arguments for Indo-Tocharian from phonology, morphology and lexicon are analysed and evaluated according to the criteria of identifiability, unidirectionality and salience. Although the Indo-Tocharian hypothesis remains attractive, it appears that progress in reconstruction mostly brings Tocharian closer to Core Indo-European than to Anatolian. Tocharian probably split off second, but much later than Anatolian and not long before the remaining speech community started to disintegrate.