Which Chinese dynasties did extensive work on building the great wall of china?

- The first emperor of the Qin Dynasty, Qin Shi Huang, is often credited with building the first version of the Great Wall.

- He connected existing walls and fortifications into one continuous structure to protect against Xiongnu nomadic tribes from the north.

Han Dynasty (206 BCE–220 CE):

- Expanded and strengthened the Great Wall to further secure its northern borders.

- Constructed watchtowers, garrison stations, and communication systems along the wall.

Ming Dynasty (1368–1644 CE):

- Undertook the most significant reconstruction of the Great Wall.

- Rebuilt large sections of the wall using bricks and stone to make it more durable and long-lasting.

- Added watchtowers, gates, and signal systems.

- The Great Wall we see today largely comes from the Ming Dynasty construction.