Answer:
The Columbian Exchange: goods introduced by Europe, produced in New World. As Europeans traversed the Atlantic, they brought with them plants, animals, and diseases that changed lives and landscapes on both sides of the ocean. These two-way exchanges between the Americas and Europe/Africa are known collectively as the Columbian Exchange.
Explanation:
The exact date is unknown but between 550 bc and 539 bc.
When unions were first organized, union leaders were in competition with one another in order to get the most active labor members, but they soon realized that this was a failing tactic and often united into single groups.