Because we seriously believed we had everything. Think about the stuff the Spanish and the English people wanted when they sailed off:
因为我们非常相信我们已经拥有了一切。想想西班牙人和英国人起航时想要的东西：
Spices? Had those
香料？有了
Silk? We basically invented it.
丝绸？是我们发明的。
Gold? Plenty!
黄金？太多了！
Silver? Shit load of.
白银？到处都是。
Farm land? Miles and miles and miles…
农场？一望无际……
Large amount of cheap labor? More than enough.
大量的廉价劳动力？供不应求。
Natural resources? Which kind? Never mind… we have them all.
自然资源？哪一种？无所谓……我们都有。
And on the flip side:
另一方面：
Religious oppression? Nope, don’t care about religion. You believe whatever shit you want, just obey our laws and don’t rebel against government.
宗教压迫？不，不关心宗教。你可以相信一切你想相信的，只要遵守我们的法律并且不要造反。
Need land for penal colony? Nope, we execute our prisoners each fall, the rest get to serve in the army.
需要土地作为流放地？不，我们每年秋天处死我们的囚犯，其余的去服兵役。
Land too poor, can’t support local population? Nope. OK, some lands might be poor, there’re definitely bad years, but moving around usually means cross the mountain, not sailing across the ocean.
土地太贫瘠，无法支撑本地人口？不。好吧，一些土地可能是很贫瘠，肯定有荒年，但四处走动通常意味着翻山越岭，而不是渡海跨洋。
Do you know what China did need at the time?
你想知道当时中国需要什么？
Trade. So we sent out a big fleet to discover trade routes, and we brought back shit China didn't have….
贸易。所以我们派出了一支大舰队去探索贸易路线，然后带回了一堆中国没有的狗屎……
Giraffes!
长颈鹿！
Zheng He be like: Your Highness! Just look at it!!! Isn’t it cute? Have you ever seen such thing before?
郑和：陛下！看呐！它不可爱吗？您之前见过这玩意儿吗？
And the Ming emperor be like: Hell No!!! Love this shit! I’m gonna name it 长颈鹿 (long neck deer) because it looks like a deer but has long neck! Totally worth the trip! Here’s more money, go bring back more cute stuff and open some ports so we can trade with them.
大明皇帝：当然不！！朕就喜欢这口味的！朕要把它叫做长颈鹿，因为它长得像鹿却有个长脖子！这一趟太值了！给你更多的钱，去给朕带回更多可爱的东西，然后开放港口，如此便可与外夷通有无了。
We don’t need colonies, we don’t need labors and economic crops to support our dying economy back home.
我们不需要殖民地，我们不需要劳动力和经济作物来支撑我们垂死的经济回到家。
So, we didn’t colonize places.
所以，我们没有殖民地。
Didn't the emperor who followed the one who commissioned those fleets end up stopping most naval trade and expeditions, essentially slowing Chinese economic growth and cutting it off from the world? He adopted a very “China first” strategy and wanted to focus on domestic issues… but as a result ended up scrapping one of the most powerful naval merchant fleets in the world and closing China off to technological innovation that was happening in other nation states.
这个皇帝不是听从谏言，终止了船队的海上贸易和探险活动，根本上减缓了中国的经济发展，并使得它与世隔绝吗？他接受了一个十分“中国优先”的战略，希望关注国内问题……但是因此废弃了世界上最强大的海上商船队之一，使得中国无法进行发生在其他国家的技术创新。
Full disclosure: I have a thing for giraffes. I buy my baby all things giraffe or giraffe-patterned. Does he like giraffes? I don't know—He's 2 months old!
坦诚地说：我有很多和长颈鹿有关的东西。我给我的宝宝买了很多长颈鹿的或有长颈鹿图案的东西。他喜欢长颈鹿吗？我不知道——他才两个月！