"being something (such as money or a commodity) of such a nature that one part or quantity may be replaced by another equal part or quantity in paying a debt or settling an account Oil, wheat, and lumber are fungible commodities." M-W.
Fungible is both adjective and noun. If used as a noun, it would mean something that could not enter into a transaction.
"Native Americans did not consider land to be fungible."
At least one historian has found "fungible land" to be an incisive economic concept. The following is excerpted from a review of Garrett A. Sullivan's, The Drama of Landscape: Land, Property, and Social Relations on the Early Modern Stage Stanford: Stanford University Press, 1998. vii + 292 pp. $39.50. ISBN: 0-8047-3303-1. https://www.thefreelibrary.com/Theatre%2C+Finance+and+Society+in+Early+Modern+England+%26+The+Drama+of+...-a066123114
"Sullivan's The Drama of Landscape, by contrast, tends more toward a methodology of accretion, mosaic or "bricolage" in which a very wide variety of disparate textual materials, including atlases, estate surveys, ballads and pamphlets, legal documents, and of course plays and poems, are joined into a rich tapestry of social description. The book is divided into three broad sections focusing respectively on estates, on roads, and on the city; and within these sections individual chapters consider one or two early modern plays along with a variety of other materials. While the analysis here remains, as Sullivan concedes, within a broadly "new historicist" tradition of literary analysis, the sheer breadth and unexpectedness of its evidence finally allows the book to transcend the technique of juxtaposition and to reach toward a kind of holistic approach. Sullivan calls on the simultaneous aesthetic and geographic senses of his titular term landscape, using the word as a rubrick for a historical process, at once material and symbolic, in which both literal property relations and the ideological valence of land were drastically transformed. In particular, Sullivan follows the discursive traces of a historical evolution in which what he calls landscapes of "stewardship" or "custom" (in which land is understood as manifesting social relations and moral obligations) were finally transformed into landscapes of "absolute property" (in which land is understood as a fungible economic object, and an object of economic development and profit). Here again, Sullivan's three "landscapes" refer usefully both to the changing forms of land tenure, and to the changing ways in which such changes were seen...."
The concept of land manifesting social relations and moral obligations equally reflects Native American attitudes toward land. They did not see land as "absolute property."