Island hopping.
Because of the Pacific Islands
China's first great canal system, which created a northeast-southwest link from the Huang He (when the Huang had a northern course) to the Huai River, was built beginning in 605 during the Sui dynasty<span> (</span>
Answer:
Before secession, there were 11 states in the United States of America. This is in the 1860's btw
Tycho brahes collecting data that enabled Kepler to discover the laws of planetary motion.