How Japan saved its biggest city from collapse - Roman Krznaric

400 years ago, modern-day Tokyo was known as Edo, and it was already one of the biggest cities in the world, with a population approaching 1 million.

However, it was on the verge of ecological collapse.

Years of intense logging had led to massive deforestation.

The city now faced timber shortages and the impacts of severe erosion and frequent flooding that threatened food supplies.

But over just a few decades, Edo will transform and become one of the most sustainable and efficient cities in history.

So, how did this city that wasted nothing come about?

In 1467, Japan entered a series of continuous bloody civil wars that would last over a century.