instruction:
This task is about creating an unanswerable question based on a given passage. Construct a question that looks relevant to the given context but is unanswerable. Following are a few suggestions about how to create unanswerable questions:
(i) create questions which require satisfying a constraint that is not mentioned in the passage
(ii) create questions which require information beyond what is provided in the passage in order to answer
(iii) replace an existing entity, number, date mentioned in the passage with other entity, number, date and use it in the question
(iv) create a question which is answerable from the passage and then replace one or two words by their antonyms or insert/remove negation words to make it unanswerable.
question:
Passage: The migration-period peoples who later coalesced into a "German" ethnicity were the Germanic tribes of the Saxons, Franci, Thuringii, Alamanni and Bavarii. These five tribes, sometimes with inclusion of the Frisians, are considered as the major groups to take part in the formation of the Germans. The varieties of the German language are still divided up into these groups. Linguists distinguish low Saxon, Franconian, Bavarian, Thuringian and Alemannic varieties in modern German. By the 9th century, the large tribes which lived on the territory of modern Germany had been united under the rule of the Frankish king Charlemagne, known in German as Karl der Große. Much of what is now Eastern Germany became Slavonic-speaking (Sorbs and Veleti), after these areas were vacated by Germanic tribes (Vandals, Lombards, Burgundians and Suebi amongst others) which had migrated into the former areas of the Roman Empire.
answer:
What modern ethnic group was formed by 6 migrating tribes?


question:
Passage: In 1906, the tungsten filament was introduced. Tungsten metal was initially not available in a form that allowed it to be drawn into fine wires. Filaments made from sintered tungsten powder were quite fragile. By 1910, a process was developed by William D. Coolidge at General Electric for production of a ductile form of tungsten. The process required pressing tungsten powder into bars, then several steps of sintering, swaging, and then wire drawing. It was found that very pure tungsten formed filaments that sagged in use, and that a very small "doping" treatment with potassium, silicon, and aluminium oxides at the level of a few hundred parts per million greatly improved the life and durability of the tungsten filaments.
answer:
What was introduced in 1900?


question:
Passage: From the late 1340s onwards, people in the countryside suffered from frequent natural disasters such as droughts, floods and the resulting famines, and the government's lack of effective policy led to a loss of popular support. In 1351, the Red Turban Rebellion started and grew into a nationwide uprising. In 1354, when Toghtogha led a large army to crush the Red Turban rebels, Toghun Temür suddenly dismissed him for fear of betrayal. This resulted in Toghun Temür's restoration of power on the one hand and a rapid weakening of the central government on the other. He had no choice but to rely on local warlords' military power, and gradually lost his interest in politics and ceased to intervene in political struggles. He fled north to Shangdu from Khanbaliq (present-day Beijing) in 1368 after the approach of the forces of the Míng dynasty (1368–1644), founded by Zhu Yuanzhang in the south. He had tried to regain Khanbaliq, which eventually failed; he died in Yingchang (located in present-day Inner Mongolia) two years later (1370). Yingchang was seized by the Ming shortly after his death. Some royal family members still lived in Henan today.
answer:

 When did the Yuan people suffer a series of unnatural disasters?