The phoneme /l/ is one of the phonemes of Persian, which has different origins. a few of which is unknown.
This article studies the historical change of /l/ phoneme and phonemes and clusters which are the origins of /l/, from Proto Indo- European to Indo- Iranian, Old Iranian and Middle and new Persian. In adition, the historical change of other phonems such as group of consonants , which are origins of /l/ in new Persian has been studied. Finally, a few examples from /l/ in proto Indo- European and new Persian are introduced to classify of /l/ words in new Persian.