Task: Question Generation
Input (English): Passage: Anaukpetlun then brought trans-Salween Shan states under his rule in the 1620s. In February 1622, his forces  took Kengtung, which had been held by an ally of Lan Xang, after a fierce battle. Reinforced Burmese armies led by the king's brothers Thalun and Minye Kyawswa II invaded the Chinese Shan states in present-day southern Yunnan in May 1622. For the next 20 months, Burmese forces chased Kenghung troops. Finally in January 1624, Kenghung and Kengyun both surrendered. Kengyun promptly rebelled the following year but it was put down in December 1626 by the king's brothers. By then, Nyaungyan and Anaukpetlun had restored much of Bayinnaung's empire. Only Siam and Lan Xang remained outside the Restored Toungoo Empire. But the Burmese would not overstretch again. They would not launch major invasions against these neighbours until the 1760s.
Output (English): How many years did it take to put the Kengyun rebellion down?