Leviticus 25:13 "In the year of this Jubilee, you shall return every man to his possession"

When the Jewish people entered and conquered Eretz Yisrael, they were instructed by HaShem to divide the country between all the tribes. Each one was assigned his precise territory.

Over the years, land could have been sold or transferred, allowing people descending from one tribe to purchase property originally owned by another tribe.

Upon the arrival of the Yovel, all property was to be returned to its original owner.