And it came to pass, when the sun went down and it was dark, that behold, there appeared a smoking oven and a burning torch that passed between those pieces. On the same day the Lord made a covenant with Abram, saying:“To your descendants I have given this land, from the river of Egypt to the great river, the River Euphrates..." Gen 15:17,18
The day began at sundown. It seems strange to us, but this is the convention from the very first day in Genesis 1. The covenant was made at the very beginning of a new day!
If you read the text before and after, we have here an oral promise to Abraham, a prophecy that was fulfilled when Moses wrote this text( the Exodus ), and a legal deed executed for property that has not yet come to pass.
If you look at a map, this territory from the Nile to the Euphrates dwarfs the current state of Israel, and includes all of Saudi Arabia and parts of Iraq. The promise is to the descendants of Abraham.
It is highly significant that Hagar and Abraham both receive promises of numerous seed.(And the angel of Yahweh said to her, “I will greatly multiply your offspring, so that they cannot be counted for their abundance.” Gen 16:10 - on command that she return to submit herself to Sarai's authority).
Just as we have 12 tribes from Israel, we have 12 kings from Ishmael. ( "And God said, “No, but Sarah your wife shall bear a son for you, and you shall call his name Isaac. And I will establish my covenant with him as an everlasting covenant to his offspring after him. 20 And as for Ishmael, I have heard you. Behold, I will bless him and I will make him fruitful, and I will multiply him exceedingly. He shall father twelve princes, and I will make him a great nation. 21 But my covenant I will establish with Isaac, whom Sarah shall bear to you at this appointed time next year.” - Gen 17:19-21)
The princes of the Middle East have certainly enjoyed great blessing and prosperity. They were a great and cultured civilization, even now, their wealth is astounding, and their hostility to their Jewish brothers is also something prophesied to Hagar. They have been preserved from pagan idolatry through Gods grace, and even have a respect for their father Abraham.
In a certain sense then, the promise has held true. The land is populated and held by the descendants of Isaac and Ishmael! The prophecy came true when Israel returned to Canaan in the 4th generation. And we look for a final fulfillment when the desert shall blossom like a rose, and the King and his people will dwell in this land forever!