"A ruler named Oannes once came across the ocean accompanied by monstrous creatures, half fish, half men and taught Mesopotamian nomads the arts of agriculture, reading, writing, metalwork, in short all things that make life better. Everything in Mesopotamian civilization came from Oannes and his seafaring companians, the black-headed foreigners, the Sumerians." Herbert Wendt quoting the Seleucidian historian Berossus.
Wendt adds that "Sumerian civilization disappeard under waves of Semitic Akkadians and Amorites, Assyrians and Babylonians, Hittites, Aramaeans. Cassites, Medes, Persians and Alexandrian Greeks." He further adds that though their civilization disappeared their race didn't, "even today, their descendants live on, a dark-skinned group in the populations of Hither Asia."
Wendt thinks that the Sumerians came from the Indus. I have another theory and it's based on Diodorus tales of Osiris. "Osiris was the first, they record, to make mankind give up cannibalism…all men were glad to change their food, both because of the pleasing nature of the newly-discovered grains and because it seemed to their advantage to refrain from their butchery of one another…Of Osiris they say that, being of a beneficent turn of mind, and eager for glory, he gathered together a great army, with the intention of visiting all the inhabited earth and teaching the race of men how to cultivate the vine and sow wheat and barley; for he supposed that if he made men give up their savagery and adopt a gentle manner of life he would receive immortal honors…this did in fact take place, since not only the men of his time who received this gift, but succeeding generations as well, because of the delight which they take in the foods, which were discovered, have honored those who introduced them as gods most illustrious." Now after Osiris had established the affairs of Egypt and turned supreme power over to Isis his wife,... and when all his preparations had been completed Osiris made a vow to the gods that he would let his hair grow until he returned to Egypt, he then made his way through Ethiopia;...after this he continued his march through Arabia along the shore of the Red Sea as far as India and the limits of the inhabited world."
Could Mesopotamia's Oannes be Egypt's Osiris?
If the Sumerians came from the Indus, why would there be a need to cross the ocean. Water does not separate Pakistan from Iran. It is more likely that Oannes came form the south and not from the east.