Working with evidence is the biggest part of the 2020 AP World History Exam. Students can master the skills of using documents as evidence and analyzing their sourcing through practice. The exchange networks became global in the years from c. 1450 and c. 1750 CE as European sailors crossed the Atlantic and the Pacific Oceans. Existing exchange networks became more global, too, Europeans and the Ottomans became much more active in the Indian Ocean. The most important exchange in this period was the Columbian Exchange.