Imagine you're playing with toy cars on a narrow street, but the street is so old that it has sunk in the middle, making a little valley. This is pretty much what a sunken road looks like.
A sunken road is a path or a road that has been flattened or carved out along a slope or depression on the ground. Because the road is dug deeper into the earth than the surrounding area, it looks like a trench or a shallow ditch.
In war history, sunken roads were strategic features that provided cover for soldiers. They allowed soldiers to move around the battlefield unseen and without being exposed to enemy fire. When soldiers were walking on a sunken road, they were like people walking in the bottom of a trench. The banks on either side of the road provided cover and protection from bullets and bombs.
Overall, a sunken road can be cool to play on with toy cars, but in history, it was an important and clever way for soldiers to move safely during a war.