In all tribal cultures as far as I know, people understood that we are inseparably connected to the world around us. To live in a harmonious way, all of life was honored for the gifts they provided - the plants, the animals, the rocks, the earth, and sky. For each individual, there were supportive, protective, and healing powers to be found if one knew how to connect with them. Each person had allies in the world of nature as well as in the world of spirit. One way to find an ally in the world of the animal spirits was to do what is called a power animal journey.
Here is the information on finding your power animal. You will need a tapeplayer and a tape of drumming that is especially made for shamanic journeys. This can be ordered from The Foundation for Shamanic Studies. The tape ought to be at least an hour long. If it isn't, re-copy it twice onto another tape to make it longer. When it is time to return from your journey, the drumming will speed up, so only have that speeded up part re-copied at the very end of the tape. If it is still light outside when you do this journey, you may want to put a cloth over your eyes to make it darker. Also, some people like to use headsets to listen to the drumming.
Get comfortable in a quiet place where you won't be disturbed for at least 40 minutes. Light a candle, and then do some slow, deep breathing to fully relax. As with doing any sacred ceremony, you may want to set up a protection around yourself and state an intention that only that energy which is your true Spirit of Unconditional Love and Life Force energy be with you and given to you. It would be good also to set up a cocoon of white light around yourself before you begin which puts this in place also. You can ask for guidance and protection from Great Spirit, the Creator, God, etc. That way you are very clear what your intention is and what you will only allow into your space. Lighting white candles is a good idea as they represent light and purity.
When you are fully relaxed, imagine that you are walking along a path that leads to a special place that you have actually seen before, a place that leads into the earth. This can be a cave, a hole in the ground, a hole in a tree, a rock overhang, etc. As you imagine walking along this path, use your imaginary senses to really be there - smell the air, feel the ground underneath your feet, notice the colors and sounds around you, feel the air against your skin. Take it all in. When you get to that place which leads into the earth, which is for you alone and no one else, enter into it, again using all your senses to explore the area for a bit. Feel if the walls are smooth or rough, wet or dry - if the air is cooler, etc.
Then, you will notice that there is a long tunnel leading down into the earth from this entranceway. Follow it down deeper and deeper into the earth. Allow the journey to take you as it will. Release any need to control it. Let happens what happens and just stay present with the experience. While you follow this tunnel deeper into the earth, hold in your mind and heart the intention that this journey is for you to connect to your power animal, your medicine ally. That is what you are there for. Eventually, you will notice that the tunnel ends at another entranceway. This entranceway leads you into the world of the Animal Spirits. This world is consists only of a world of nature. Natural landscapes are everywhere. There are animals everywhere - in the trees, grasses, by the rivers, on the mountains, etc. Notice what it looks like, what the landscape is like where you have arrived into this world. Leave the tunnel and begin to walk out into this world. Again, use all your senses as you explore this world. Notice what time of day or night it is, what's around you, the sounds and colors, the smells, the feeling of the air against your skin, how the earth feels under your feet, etc. Walk in this world taking it all in, holding your intention to meet your medicine ally, until an animal approaches you. When it does, ask it if it is your power animal. If it says yes, you may then journey on with it, learning about it, sharing with it, bonding with it, and asking for any help or guidance or answers you may need. If it says no, it is not your ally, continue walking until you meet the right one.
Ask your power animal to show you what happened in that past life, and to help you resolve and heal the issues - to learn how to come ffrom the power of your Spirit, the power of Love. When it is time to leave this spirit world, ask your power animal for a gift, and give it a gift in return. Ask how you can call upon it when you need to, and ask also if you need to keep what it is and what it shares with you private. When it is time to go, say goodbye, and thank you.
Then, return to the tunnel and walk back up out of the passageway until you return to the entrance where you entered into the earth. Walk back along your path, and return to the room where you are visioning from. Take some time to fully come back into your body, bringing ALL of yourself back, filling up all of your body with yourself, all the way to finger tips and toes and eyelashes. If you choose to, you can write in a journal about what you learned and what guidance you were given. Take some time to integrate this experience. Don't go out into the world too fast or try to do too much afterwards. Drink water, and remember to blow out the candles!