You definitely noticed that Theravada monks in Southeast Asia wear those emblematic saffron orange robes, here’s why.
This is simply due to the beginning of this tradition going back 25 centuries ago, to the time of the historical Buddha. Robes were patched together from unwanted clothes: rags that were then trimmed and washed. The cloth was then dyed by being boiled with what was available at the time: tubers, bark, flowers, leaves, and spices such as turmeric or saffron, which gave it its particular color.
The color can vary depending on the dye used, coming from different roots or trees. Today, more and more robes and dyed with chemicals, which gives it this brighter orange (especially in Bangkok).
This is different from the rare ordained Theravada women who wear muted colors like pink or white, and the Tibetan monks wear brown robes.
The robes themselves are symbolizing simplicity and detachment of materialism, along with other rules of living, such as shaving their heads. It’s that simple!