Q: 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.
Passage: It was temporarily under the control of the Tibetan empire and Chinese from 650680 and then under the control of the Umayyads in 710. The Samanid Empire, 819 to 999, restored Persian control of the region and enlarged the cities of Samarkand and Bukhara (both cities are today part of Uzbekistan) which became the cultural centers of Iran and the region was known as Khorasan. The Kara-Khanid Khanate conquered Transoxania (which corresponds approximately with modern-day Uzbekistan, Tajikistan, southern Kyrgyzstan and southwest Kazakhstan) and ruled between 9991211. Their arrival in Transoxania signaled a definitive shift from Iranian to Turkic predominance in Central Asia, but gradually the Kara-khanids became assimilated into the Perso-Arab Muslim culture of the region.
A:
Who restored Polish control of the region?