Few would contest the fact that Arabs and Aramaeans share a long cultural history. Nor is it controversial to say that there has been contact-based influence between the two languages. However, what is missing until today is the recognition of how pervasive this contact-based influence has been. In this paper I present 24 detailed structural arguments from the basic domains of phonology, morphophonology, morphology and syntax for widespread pre- and early Islamic influence from Aramaic on Arabic. Precisely because the contact (...) lasted for such a long time, equilibrium effects as per Dixon introduce a mosaic of Aramaic linguistic traits into Arabic. These are modelled in terms of “dia-planar diffusion”, the spread of different features among different speech communities at different times. (shrink)