This root was the basis for “land” words for much of Tolkien’s life. It first appeared in a deleted note from the Qenya Lexicon of the 1910s: “Nōre, -nor land is different from family, one = Gnome Dor, other Gor. NᵈOR and NGOR”; the editors indicate that the superscript “ᵈ” was a later addition (QL/67). The Poetic and Mythological Words of Eldarissa also mention nᵈor and ŋor as the basis for ᴱQ. nóre (PE12/66, 67). However in the Qenya Lexicon proper, ᴱQ. nóre “native land, nation, family, country” was given under the root ᴱ√NŌ “become, be born” with variant ᴱ√NDO; the root was originally given as ŊŌ (QL/66). Thus it seems the two roots NDO(R) and ŊO(R) were combined. In the contemporaneous Gnomish Lexicon, G. dôr “land, country (inhabited), people of the land” appeared, probably from NDO(R) (GL/30), whereas “family, kinship” was nothri instead, almost certainly from ᴱ√NŌ given its relationship to G. nost “birth” (GL/61).
The two roots were separated again in The Etymologies of the 1930s where the root ᴹ√NDOR “dwell, stay, rest, abide” was the proper basis for “land” words, but in Quenya was blended with nóre “clan, race” from the root ᴹ√NŌ “beget” (Ety/NDOR, NŌ). This derivation allowed Tolkien to retain his preferred suffixes Q. -nóre/-nor vs. N./S. -dor for “-land”, and he mentioned this parallel derivation several times in later writings (PE17/26, 106-107; WJ/413 note #25). The only later change was in the gradual refinement of the meaning of NDOR as more properly referring to (dry) land as opposed to water, seas and swamps (PE17/106, 181), properly a strengthened form of √DOR “hard, tough” (PE17/181; WJ/413).