Foreigners, foreign lands and aliens can represent some part of yourself which is unfamiliar to you. I believe your dream is about your feelings towards your father that you are only just beginning to resolve.
Although he was your Dad he feels like an alien to you. You describe the aliens as 'friendly' which is the dream's way of telling you that it's psychologically healthy resolve these feelings.
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INFO ABOUT ALIENS IN DREAMS | 
I dreamed that I was abducted by friendly aliens. They took me into their spaceship and spoke to me in a language I couldn't understand. But the tone of their voice sounded familiar. Suddenly I remembered it. Although the words made no sense I recognised the voice of my father who had died when I was a teenager. He used to speak with a broad Newcastle accent. I looked again and could see his face reflected in their eyes. Can you explain this very strange dream?