1) invasions by nomadic peoples from Central Asia" is the one unfying factor that contributed to the fall of the Han dynasty, the fall of the Roman Empire, and the
fall of the Abbasid Empire.
Explanation:
The fall of the empire and therefore the dynasty were similar as a result of each toughened social unrest throughout their collapse. The autumn of Rome and Han dynasty China were additionally similar as a result of they each round-faced roving invasions that greatly contributed to their decline.
During the Five Year Plans Stalin created an almost pure command economy. If he needed food, he requisitioned it. If that didn't work, he had the country-side searched for private stocks which he confiscated, having first killed its owners. If he wanted to build a factory in the Urals, he sent people there to build it using food and materials he had requisitioned elsewhere. He killed maybe 15 million people he thought were opposing his policies. He also inspired workers very effectively, convincing them that they were building a new type of civilization, and were in fact becoming a new and better type of human being. He was helped in this endeavor by the fact that the entire rest of the world was manifestly against the Soviet experiment and wanted it to fail. The workers believed their lives depended on rapid industrialization, and given the rise of fascism, and their leaders murderous resolve, they were right.
It is noted that now 27 countries of the world peg their currencies to EURO. So the answer is EURO.
