What does it mean to be constantly chased by a gang of people in your dreams?

It is most likely about childhood fears. How old is your sister in the dream? That will be a clue about when the fears began.You may have been a fearful child. If you can face the the gang now you might be able to move past this fear. Program yourself before going to sleep: How can I face these people? I want to turn and face them. Your guides will knowledge your request by giving you more clues. It may take several nights and dreams to get yourself to turn and face them. An alternate take on this one: there may be some negative influences (the gang of men) from the past that you need to let go. It could be related to male qualities that were pushed on you as a child, or that have formed your male values today. Their use has been exhausted, you need to eliminate these negative influences to be free from the nightmares. The fact that they are faceless means you have not faced these issues.  I don't usually give advice along with an interpretation, but because the fear and exhaustion you experience are so intense and physical, you may want professional help going through this. Your sister may be able to help you,. The events or issues would have developed around the age of you sister in the dream.