Source : Webster's Revised Unabridged Dictionary (1913)

Contemporaneously \Con*tem`po*ra"ne*ous*ly\, adv.
   At the same time with some other event.

Source : WordNet®

contemporaneously
     adv : during the same period of time; "contemporaneously, or
           possibly a little later, there developed a great
           Sumerian civilisation"