Complex sentence: However, the concept of "Soviet nation" did not use the term that had heretofore been used for a "nation"--natsiya, нация--but rather the word for a "people": narod (народ).
Split into simpler sentences: However, the concept of "Soviet nation" did not use the term that had heretofore been used for a "nation": natsiya (нация). Instead it used the word for a "people": narod (народ).