It wasn't just a simple case of drawing lines on a map. It was a complex process, deeply intertwined with conquest, settlement, and, of course, divine promise.

Our text from Sifrei Devarim 51, a portion of the legal commentary on Deuteronomy, delves into this very question. It's a fascinating exploration of how far the Israelites' claim extended, particularly in relation to lands conquered outside the core territory of Eretz Yisrael. : what happens when you conquer land near a natural border like a desert, a river, or the sea? Does that natural boundary then become your border?

The text uses Deuteronomy 11:24 as its starting point: "From the desert and the Lebanon, from the river, the river Perath, until the western sea shall be your border."

But here's the twist. The text emphasizes a subtle but crucial distinction. "From the desert," it says, "but the desert (itself) is not your border." Similarly with the river and the sea. Unless… unless you’ve conquered territory right up to those natural boundaries. If you have, then that natural boundary does become your border.

So, the desert isn't inherently the border. The river isn't inherently the border. The sea isn't inherently the border. But conquest changes things. It extends the reach of the promised land. It’s all about how far they pushed, how far they settled.

This idea is reinforced by Numbers 34:6: "And (what is) the western border? The Great Sea (the Mediterranean) and the bounds (i.e., the islands within it) shall be for you. This shall be the western border for you." The Great Sea, also known as the Mediterranean, and even the islands within it, could potentially become part of the border if conquered and settled.

But it doesn't stop there. The text goes on to discuss the implications of who did the conquering and when. It distinguishes between those who came up from Bavel (Babylon) and those who came up from Egypt. This refers to different periods of return and resettlement after periods of exile.

The text states that any land seized from Eretz Yisrael by those returning from Bavel, up to a place called Keziv, had specific agricultural restrictions. The fruits of shevi'ith, the Sabbatical year, could not be eaten, and the land could not be worked. Shevi'ith refers to the seventh year in a seven-year agricultural cycle mandated by the Torah, during which the land is left to lie fallow and debts are forgiven.

Those returning from Egypt, however, had slightly different rules applied to their conquered lands. The fruits could be eaten, but the land still could not be worked during the shevi'ith year. This difference likely reflects varying rabbinical interpretations and enactments at different times. It highlights how the application of religious law could be adapted to specific historical and social circumstances.

What does this tell us? It's not just about physical borders on a map. It's about the relationship between the people, the land, and the divine covenant. It's about how conquest, settlement, and religious law all worked together to shape the very definition of Eretz Yisrael. It's a reminder that borders, both physical and spiritual, are often the result of a complex interplay of factors, evolving over time and reflecting the ever-changing story of a people and their land.