Southern Shaolin, like Choy Li Fut, seems like it was formed by people familiar with fighting in confined spaced, narrow corridors, and tight corners.
Northern Shaolin, on the other hand, seems like it was formed for wide open fields of battle, spear training particularly.
Liuhe (Six Harmonies) style of Xingyi seems like it might have developed on narrow rice paddy pathways.
Baguazhang is harder to place, but from my experience walking in the mountains, I would say there is a strong case to be made that carrying something around on narrow or steep mountain ledges is a likely possible origin.
Taijiquan comes out of the water.
Years ago I had the opportunity to meet Willem de Thouars who, as a child in Indonesia, studied Silat. After achieving a significant level of martial skill at an early age, his family told him to ask the Chinese people living down the road if they would teach him.
The man he ended up studying with eventually taught him Baguazhang, Taijiquan and other arts. The teacher's first condition for allowing young Willem to become a student was for him to go to the river and jump off of the bridge onto the slippery floating logs that were part of a local logging operation and balance there. He said it took a long time to learn and it was very brutal.
(If you are not going to try this method yourself, at least think about what it would feel like. How relaxed do your legs need to be? How much mobility do you need in your torso?)
If you've watched all my Youtube videos you know that I have a little experience fighting on fishing boats in Alaska. The first couple of times I went to sea, I got seasick, but with a little coaching I learned. To avoid seasickness first you have to keep your eyes gazing out on the horizon. Looking at the boat or the water will make you sick. This is very simular to the kind of vision we use in Taijiquan, we soften our focus and gaze way off into the distance.
The second part of not getting seasick is just relaxation. If you try to "hold" your balance, or "hold" your internal organs in place, you will vomit. You have to just let your whole body move around on its own. Trust the rolling of the sea-- again, very simular to taijiquan practice.
We worked 20 hour shifts on one of the worst fishing boat in the fleet (worst because the skipper's brain wasn't equipt with the re-evaluation process). All the guys got sore knees, except yours truly.
The secret to my knees not hurting like everyone else's was that I was rolling my dantian and keeping my knees bent the whole time I was on the boat. At that time, when I wasn't working 20 hours, I was doing about 4 hours a day of Chen Style Taijiquan Chansijin (silk reeling exercises).
When I came back to San Francisco my teacher at the time said to my fellow students (probably hoping another student would use his words as an excuse to challenge me to a fight), "You all have been practicing here with me all Summer, the Priest (that's what he liked to call me) has been away in Alaska and he has progressed more than any of you have." (Yikes, competitiveness encouraged.)
The last thing I want to say about water is that if you've ever poled a boat through the water or used a Chinese style stern oar, you might have noticed that it is a lot like the Taijiquan movement, "Grasp the Birds Tail."
Oh, O.K., one more thing. If the founders of Taijiquan were actually fisherman, then it would explain how the modern day practitioners' picked up the habit of exaggerating (the size of the fish that got away).