Oh, most Assur-edly. But seriously though, that depends on what you mean by “the earliest-known”. Which specific cultures are you referring to? Sumerian was the de facto lingua franca (for written language) until superseded by Assyrian, and in either case, warfare between city-states and proto-states was full on raging basically since the beginning until, well, now. So they were quite aware. The Mesopotamian delta is only so big, you’ve got the two main trading and shipping arteries running through the desert, Eufrat and Tigris, making it super lush and pretty, so generally those were the areas fought over (though back then even the desert wasn’t quite as desert-y as it is today, and there’s plenty of ruins in the middle of bumfuck sandland, though arguably they wouldn’t have settled there without a good source of water. The Assyrians built some sick-ass aqueducts, too, but let’s not talk about them because they were not very nice people).
How about whether or not the earliest-known literate civilizations in the ancient Near East were of each other’s existence?
Oh, most Assur-edly. But seriously though, that depends on what you mean by “the earliest-known”. Which specific cultures are you referring to? Sumerian was the de facto lingua franca (for written language) until superseded by Assyrian, and in either case, warfare between city-states and proto-states was full on raging basically since the beginning until, well, now. So they were quite aware. The Mesopotamian delta is only so big, you’ve got the two main trading and shipping arteries running through the desert, Eufrat and Tigris, making it super lush and pretty, so generally those were the areas fought over (though back then even the desert wasn’t quite as desert-y as it is today, and there’s plenty of ruins in the middle of bumfuck sandland, though arguably they wouldn’t have settled there without a good source of water. The Assyrians built some sick-ass aqueducts, too, but let’s not talk about them because they were not very nice people).