A brief, relatively competent academic monograph, based largely on secondary sources, dealing with the trade links between Egypt and Mesopotamia in the Predynastic period. Both civilizations were, of course, river-valley civilizations -- Egypt spread south into Nubia and into the southern reaches of the Delta; Mesopotamian north into Iran and Syria. Most of the trade, according to Mark, was conducted through an overland route that went from Northern Mesopotamia to Egypt via Syria/Palestine or through a sea route from Syria to Egypt. In other words, most of the very early, Predynastic Egyptian/Mesopotamian trade was indirect (via Syria) and skirted the coast either by sea or by land.
Trade through the Gulf and Red Sea is attested, but is not significant in the predynastic period.