Let's learn some Mongolian language and history

This seems quite informative and accurate about Mongolian history and language:

"What Genghis Khan's Mongolian Sounded Like – and how we know"

Bathrobe comments:

He mentioned things that only someone who had done a study of Mongolian would think of (such as the fact that 'n' at the end of words is now pronounced 'ŋ'), which I found impressive.

I was also impressed that he looked beyond Khalkha Mongolian in looking at the language. Mongolia itself is stiflingly Khalkha in its outlook.

Here's an enigma for me:

Why is Mongolian still very much a living language, whereas Manchu is essentially extinct?

Both are "Altaic" languages, both use scripts based on the Old Uyghur alphabet, which was in turn ultimately derived from the Aramaic alphabet, the Manchu script being an adaptation of the Mongol script.

Having united the steppe tribes, Genghis Khan established an empire of about a million people.  The Mongols conquered much of Eurasia, with around a hundred million population, but only ruled over China for less than a century (1279–1368), and that was more than seven hundred years ago.  In contrast, Manchu conquests were confined to the eastern part of Eurasia, but they ruled over China for more than two and a half centuries (1644–1912), and their Qing Dynasty lasted into the 20th century.

The Manchu ethnicity still has more than ten million people, and they were able to control the population of the Qing realm, which grew from around 150 million to 450 million under their reign.

Again I ask, why is Mongolian still a living language, whereas Manchu (with one exception; see Reading) is no longer alive?

Reading

"Sibe: a living Manchu language" (9/30/17)