Using　the　Solar　Dynamics　Observatory　observations,　we　study　the　evolution　of　an　emerging　active　region　(EAR)　and　its　reconnection　with　the　quiet　Sun.　The　EAR　continuously　interacts　with　the　surrounding　quiet　region,　and　dark　ribbons　at　the　boundary　of　the　EAR　and　the　quiet　Sun　are　observed.　The　extreme-ultraviolet　observations　show　that　the　regions　swept　by　the　dark　ribbons　are　brightened　and　the　temperature　increases.　These　results　reveal　that　there　exists　an　uninterrupted　magnetic　reconnection　between　the　EAR　and　the　quiet　region　and　the　released　energy　heats　the　corona　of　the　quiet　Sun.　The　dark　ribbons　are　suggested　to　correspond　to　the　interface　of　the　reconnected　fields　and　the　undisturbed　ones.　The　dark　ribbon　propagates　outward,　and　this　phenomenon　is　considered　as　a　dark　wave.