Ancient China was isolated geographically by mountains, oceans, and deserts which protected it but also limited trade and exchange of ideas. Mountains along its eastern border, oceans to the west including the Pacific and seas, and the Gobi Desert to the north all naturally separated China. The Great Wall was later built for additional man-made isolation and defense from northern threats like Mongol invaders. While isolation provided protection, it also restricted economic growth through trade and exposure of Chinese citizens to outside information.