1. Sun Tzu said: We may distinguish six kinds of terrain, to wit: (1) Accessible ground; (2) entangling ground; (3) temporizing ground; (4) narrow passes; (5) precipitous heights; (6) positions at a great distance from the enemy.
Ground which can be freely traversed by both sides is called accessible.
For soldiers fighting throughout history, “terrain” referred to the physical ground they were fighting on. In the modern world it can refer to the economic environment. Both have the same effects. Some terrain can be altered and some cannot.
It did not take long since the development of the internet for people to realise that they could make money online. The market was extremely accessible with low barriers to entry meaning it was easier to make money than ever before.
However, cheap costs and accessible conditions meant the market soon contained lots of competitors, all vying for a piece of the financial pie.
Be aware that if something is accessible to you, it may be accessible to your enemies too. If you reach the top, it could be easy for somebody to take that spot away from you.
2. Ground which can be abandoned but is hard to re-occupy is called entangling.
Battle of Maryang San, Korea, 1951
The Chinese had taken a key hill in the Korean War from the US and Canadian armies. After trying to recapture the hill without success, they eventually sent up a scouting and sniper team led by French Canadian Léo Major.
By silently climbing the hill, they then used the cover of darkness to open fire and panic the Chinese troops who were expecting the attack to come from outside their territory rather than from within it. This barrage helped the team finally recapture the hill in the early hours.
Ground that is hard to re-occupy such as a hill, forest or a market monopoly are important to keep once you occupy them. As it is good to defend entangling ground, you should attempt to prevent enemies from taking it.