Either the second or third ones
They made Channels underground a lined with clay to prevent sepage in the surrounding soil. They were a big contribution and we still do something inspired by that today.
Answer:
October 12, 1492
Explanation:
Columbus left Castile in August 1492 with three ships, and made landfall in the Americas on 12 October (ending the period of human habitation in the Americas now referred to as the pre-Columbian era). His landing place was an island in the Bahamas, known by its native inhabitants as Guanahani.
Answer:
The Cuo recommends to detect intrusion of enemies by surrounding them by sandy fields.
Explanation:
Chao Cuo was a Chinese politician, philosopher and writer who worked during the Han Dynasty. Many of his writings address the Xiongnu nomads of the North, who were a pressing concern for China during the Han dynasty. He also proposed a policy that would populate and defend frontier zones. The advisor was murdered in an attempt to mitigate the Rebellion of the Seven States.
