(Bamidbar 34:12) "The land according to its borders all around" (Bechoros 55a) This teaches that all of Eretz Yisrael is considered one border.
Even though each tribe received a portion with prescribed boundaries as written in Sefer Yehoshua, nevertheless, the entire land was considered as if one bordered property.
T.T. The practical difference is in regards to the law of Maaser of one’s animals. If one owns 10 or more animals, you place the animals in a fenced area, and as they exit, the 10th animal becomes Maaser. If you have five animals in Eretz Yisrael, and five outside of the land, they are not joined together to be obligated. However, if one has five animals in one Tribe’s portion and another five within close proximity (16 mil) but in another Tribe’s portion, one does connect them and is obligated in Maaser. This is due to this concept that the whole land is considered one set of bordered property.
(Bamidbar 34:15) "Across the Jordan, Jericho" (Bechoros 55a) The Jordan is compared to Jericho; just as Jericho is land, so too the Jordan is land.
T.T. Same practical difference as above regarding Maaser of one’s animals. This is to say that Yardein has the same law as the Land of Israel. If one person owns five animals on the West side of the Yardein river and also five animals on the East side of the Yardein river, he performs Maaser.
