That's a good question, though the timeline of the two games doesn't seem to make any sense at all within Tolkien's legendarium. I know that Talion was supposed to be a Ranger of Gondor during the Third Age. Shadow of Mordor has Gollum assisting Sauron in perfecting the One Ring even though the Ring was forged in the middle of the Second Age, thousands of years before Sméagol was born. Plus characters of the Third Age as Ringwraiths even though the Nazgûl first appeared in the Second Age.
That's a good question, though the timeline of the two games doesn't seem to make any sense at all within Tolkien's legendarium. I know that Talion was supposed to be a Ranger of Gondor during the Third Age. Shadow of Mordor has Gollum assisting Sauron in perfecting the One Ring even though the Ring was forged in the middle of the Second Age, thousands of years before Sméagol was born. Plus characters of the Third Age as Ringwraiths even though the Nazgûl first appeared in the Second Age.