KanjiJLPT N1
Barbarian

barbarian, foreign

Mnemonic

The old moon hangs over the steppe — the only witness to every barbarian raid in history. It grew old watching wild horsemen howl at the moon before thundering south. Each barbarian horde aged the moon a little more, cracking its ancient face.
Additional thoughts
Picture a cracked, weathered moon looming over endless grasslands, its surface worn ancient by millennia of barbarian war cries echoing upward. Old + Moon = Barbarian.
Quick recall
The old moon grew ancient watching every barbarian horde howl beneath it.

Details

The keyword for 胡 is barbarian. This kanji historically referred to the non-Chinese peoples living to the north and west of ancient China, particularly the nomadic tribes of Central Asia. It carried connotations of foreignness and was used broadly to describe things considered exotic or non-native. Over time, it also came to be used in a more general sense meaning reckless, random, or nonsensical, as in acting without reason or order.
On'yomi
う、こ、ご
Kun'yomi
なんぞ