Definition: This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
Input: Mieszko I of Poland (c. 935 – 25 May 992) established an elite knightly retinue from within his army, which he depended upon for success in uniting the Lekhitic tribes and preserving the unity of his state. Documented proof exists of Mieszko I's successors utilizing such a retinue, as well.
Output:
WHo established an elite knightly retinue?