Complex sentence: Negan's existence is confirmed in the mid-season finale "Start to Finish", when Daryl, Abraham, and Sasha are forced to stop on their way back to Alexandria by a group of heavily armed men on motorcycles blocking the road.
Split into simpler sentences: Negan's existence is confirmed in the mid-season finale "Start to Finish", when Daryl, Abraham, and Sasha are on their way back to Alexandria. They are forced to stop, however, when they come upon a group of heavily armed men on motorcycles blocking the road.