Both Andrew Carnegie Mellon and Henry Clay Frick were industrialists and business partners. Carnegie produced steel and Frick manufactured coke (necessary to produce steel). Frick eventually became chairman of Carnegie's company, but Carnegie made several attempts to force him to renounce to his position and disregarded him, and his opinions, on numerous occasions. This is, therefore, an example of the tensions that the industrialization of the U.S. entailed (there were companies that merged with, or sometimes bought, other companies; companies that used black workers and convicts as labor; companies whose workers went on strike; and hostility towards the wealthy industrialists as well as between them).
Mao successfully led a communist revolution and the Communist Party gained power in 1947. They were appealing than the Nationalist Party as they sought preserve 'true' Communist ideology in the country by purging remnants of capitalist and traditional elements. This was supported by the peasants
What the three countries had in common was that they all had a vast military that was closely connected to the way society was developing. In addition, they had a lot of interference from European forces, often being based around religious beliefs, and this interference brought many things up to speed when it came to modernization.
Catholicism were the ones who could dictate when to start the timeline, and chose the birth of Christ as that starting point.