When the Mongols invaded China and established the Yuan dynasty, why did they outlaw intermarriage and forbid the Chinese from learning the Mongolian language?

During the first world war both sides engaged in tunnel warfare, the primary purpose of which (as far as I can tell) was to place large amounts of explosives under enemy lines and then detonate them immediately prior to ground attack. Was there ever any attempt to use a tunnel to bypass the fron...

You all know that every national flag but Nepal's is rectangular. Most coins are roundish. These are some old norms. What about paper money? The rectangular form is close to universal. After poking around numismatic resources on the web I didn't find a single historical example of a bill that ei...

I've been having some trouble understanding the importance of glass in the ancient times(BCE). What was glass' importance then?

When United States Supreme Court nominee Kavanaugh was publicly accused of a 1982 attempted rape at age 17, his defenders noted that the accuser Dr. Blasey Ford had not obtained redress by pressing charges at the time. Maryland had two relevant charges then on the books: attempted rape (a misdeme...

Why did the U.S. make 1000 dollar bills? Wouldn't the value of this money be ridiculously inflated and make the economy weak? Examples, the Zimbabwe trillion dollar bill is only actually only worth about 6 U.S. cents.

The only current page I found for this device is this Chinese one, which didn't clarify anything. It looks like she's digitizing a blueprint.

Can someone identify this uniform? I suspect it is from WW1 and was taken by an Australian photographer.. tho obviously not in Australia. It is part of a bigger historic pic.. a glass plate amongst a collection of plates which were shot around 1910-20