[...] Lingua Franca originated at the time of the Crusades (A. D.1095ff.) on the Jerusalem battlefields, later spreading westward along the shores of the Mediterranean with the military and merchant vessels.
- Hancock (1977), Pag. 283

Documentation also suggests that the term 'Franca' in the Lingua Franca is older than the Crusades. It is commonly thought that the term came into use at that time, employed by the locals of Byzantium and environs to designate the language of the crusading invaders whom they indiscriminately classified as “Franks.”
- Hancock (1977), Pag. 287