Middle markers are characterized by a distribution halfway between grammar and the lexicon: with some verbs,
middle marking encodes valency change, while with others it obligatorily occurs with no obvious synchronic motivation. Despite the
existing cross-linguistic work on middle markers, their history is still largely unknown. In the typological literature, the
standard view is that middle markers predominantly have their origin in reflexive markers, and that, in their development, it is
invariantly the grammatical component that expands to the lexical component. In this paper, I challenge these assumptions based on
the analysis of a sample of 129 middle marking languages. As I show, the sources and pathways whereby middle markers come about
are much more numerous and varied than what has been reported in the literature. By taking a source-oriented approach, I also
discuss how recurrent cross-linguistic trends in the distribution of middle markers can in part be explained by looking at their
history.