sentences:  Interest in their development declined with the advent of powered flight at the beginning of the 20th century.Man-carrying kites are believed to have been used extensively in ancient China, for both civil and military purposes and sometimes enforced as a punishment.The (636) "Book of Sui" records that the tyrant Gao Yang, Emperor Wenxuan of Northern Qi (r. 550-559), executed prisoners by ordering them to 'fly' using bamboo mats.