The first Cuban to play in the majors was Esteban (Steve) Bellan, who played in the National Association from 1871-1873.
Baseball had been introduced to Japan by American missionaries in 1873.
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That said, the state of Cuban and Japanese baseball was well below that of America’s in the 19th Century.
Cuba has probably been close to American ball for most of the 20th Century and there would have been more Cuban stars in the majors if it weren’t for segregation.
Japan is getting close to the U.S. in quality, but if you matched up the Yakult Swallows (the 2001 Japan Series champ) against the Arizona Diamondbacks, it would not be pretty. The Swallows would look even more feeble against Messrs. Schilling and Johnson than the Yankees did. They would probably hit Byung-Hyun Kim pretty well however since submarine style pitching is not uncommon in Japan.