Numbers 36:4

And when the year of jubilee came round (see Lev 25:10), their inheritance would be entirely withdrawn from the tribe of Manasseh. Strictly speaking, the hereditary property would pass at once, when the marriage took place, to the tribe into which an heiress married, and not merely at the year of jubilee. But up to the year of jubilee it was always possible that the hereditary property might revert to the tribe of Manasseh, either through the marriage being childless, or through the purchase of the inheritance. But in the year of jubilee all landed property that had been alienated was to return to its original proprietor or his heir (Lev 25:33.). In this way the transfer of an inheritance from one tribe to another, which took place in consequence of a marriage, would be established in perpetuity. And it was in this sense that the elders of the tribe of Manasseh meant that a portion of the inheritance which had fallen to them by lot would be taken away from their tribe at the year of jubilee.