Well, you had the human inhabitants who were portrayed as being distinct from those in other Imperial provinces, but they were never named 'Imperials' until Redguard. The population has always been there, and distinguished from the Nords, Redguard and Bretos (Individuals like Uriel and Tharn were never portrayed by Provincial racial identities) but they were never made a distinct Race until Redguard and Morrowind.