An Emperor game of China where through a combination of lucky semi-isolated start with gigatons of hammers nearby and the warmonger civs warring amongst themselves, I managed to spam nearly all the wonders in the world. Germany tried to put a stop to that sometime in turn 100+, after I settled my third city out of Great Wall comfort zone, but between me getting Chu-Ko-Nu and wiping out his piecemeal landknecht attacks, he... bought off all the city-states surrounding me and got them into the war.
I panicked. Then Bismarck gave me a generous peace treaty. So in that time, I made good use of it by taking out one of the closest CS Germany ally (Warsaw) and used it to connect my third city to Beijing.
Then Germany declared war again. Too bad for him I had longswords, knights AND a large pool of Chu-Ko-Nu. With them, I took a puppet city of his and waited for rifling. Chu-Ko-Nu turned into rifles, pressed onwards to Berlin. This left Germany with his Songhai puppets to the southeast, and a horribly backwards Japan.
By then I've met two other civs from other continents, Iroquois and Aztecs... and the Polynesians, but the Aztecs quickly wiped them out.
Well suffice to say, long story short, this was the state of the world in 1991:
The two other continental civs were at various points in 20th Century close to completing Apollo Program (Hiawatha completed SS Booster 1). After they met Chinese carrier groups loaded with atomics, none of them ever thought about going into Alpha Centauri.