Close. It were the Mongols who opposed a threat towards China dangerous enough to make the Chinese emperor order the creation of a massive wall along the borders.
However, as this defensive tactic proved it self quite worthwhile, the Chinese kept improving and expanding the wall, eventually holding other attackers such as the Huns at bay as well.
Mongolia is a country next to China on the north. In the early days it's inhabitants were violent nomads, mostly depending on scavenging on other countries. As the surrounding lands kept focused on farming and export, they practiced warfare and combat techniques. They didn't need to be able to produce anything themselves, they became far to good at stealing and plundering.
Forgive me, made a mistake posting Cook in the Africa thing.... It's been a long day.
Cook was the first to land on Australia, but not the first to find it. That was the Dutch Willem Janszoon, as he got of course on his way to India.
Back to the topic at hand, I believe it was Marco Polo who was the first European to set foot in Africa.